Fenrisulfr

Those are not builds. Those are powersets and archtypes.
A 'build' is the particular powers you've chosen from each powerset, your pool powers and the way that those powers are slotted.

And while I only play on Virtue, unless you're in a 'Master of' task force, or the team leader is looking to do a 'Speed Run' of something, or just wants top quality characters, or has actually advertised for something other than what you've brought:
I'm not saying that that is what happened, just that it may be a possibility, among several other possibilities.

I can't speak for most other people, though I can definitely speak for myself and in a small way, speak to those that I've teamed with.

So, here we go:

Sticking with Mids'?
Do you know another character design tool that works as well and is updated as often?
I sure don't.

Sticking with flavour builds that one min/max suggests to another?
Min/maxers like to min/max.
They also talk to other min/maxers to get more information or another persons perspective on their build.
Or they're not all that experienced with min/maxing and ask someone else to do it for them.

Getting kicked off of a team, or experiencing bias when playing uncommon builds?
First off, the team leader has the power to kick a player that they don't want on their team.
It's their team.
If they're a jerk, no one will stay on the team; if they do, they deserve what they get.

Personally, I've never seen a person kicked off due to their build.
Saying that however, there is some content where a good build is highly desirable. 'Master of' task forces, for example. If you're joining one of these, it's expected that you'll have a good build.

I can't say too much else without seeing one of these uncommon builds of yours. I know I've been playing a mercenary/thermal mastermind and have been doing fine. No complaints, or kicks.
But then again, I have taken the 'common' powers for a mastermind. Pets, heals, shields, fitness, and so on.

If you've been doing something like making a dual pistols defender with only one power from the primary and everything else from dual pistols and power pools well... those people may be entirely reasonable in their reactions.

20 Dual Pistols blasters with either energy melee or mental manipulation, all looking like mercenaries or hitmen?
You may not have heard, but Dual Pistols is the newest powerset.
As such, there are a lot of people trying it out.
The nature of dual pistols, (variable debuffs, point-blank area-of-effect ultimate with a long animation and a good amount of area-of-effect attacks) means that it works well with energy melee, (powerful melee, stuns to stack with suppressive fire and power boost) or mental manipulation. (point-blank and ranged area-of-effect attacks, drain psyche for additional survival when in close proximity to enemies)

Also, take a look at all of the blasters out there. Mental Manipulation and Energy Manipulation are probably the two most common secondaries for blasters.

People like being mercenaries and hitmen.
Some of those mercenaries could also have easily been special forces soldiers or SWAT officers. Their equipment would look similar from a distance.
Some of those hitmen could have been spies, businessmen or bodyguards. Suits and dark glasses are fairly similar looking.

Fire/kinetic controllers?
It's self-explanatory?
Good.
Think for a moment, on WHY it is self-explanatory and apply that thinking to other archtypes.

Willpower, shield defense on tankers with superstrength, mace or fire melee
Alright, this one's really more a matter of going for the best [blank], based on what other people have said.
There are other people who have played far more than me.
There are people out there who spend time crunching the numbers and working out what can tank a large group of enemies the best, or deal the best damage, or is easiest/cheapest to soft-cap defence, etc, etc.

Unless I find there's something that looks hinky, I tend to accept what they say and move on.

Also, I want to make an ice tank myself, but just can't get a character with which I can accept the ice armours' visual effects.

And war mace is common? I'd hardly noticed. It does have decent soft controls with the aoe attacks.
Superstrength has footstomp which is one of the best point-blank area-of-effect attacks and a very good damage buff in Rage.
Fire melee has good area-of-effect attacks.

Joke builds?
The powersets in a build, and the build itself are two separate things.
If a fire/kin controller only had transfusion and repel from the secondary, then it would be a bad build.
Not that a decent player couldn't play with it, just that they would be far less effective than a fire/kin who has more of their secondary.

ice/sonic controller and storm/electric blast defender?
The powersets aren't jokes. I'd have to see the builds to determine whether they're good/decent/bad in my own opinion.
If it works for you though, good.
If people don't like the builds, find people who are okay with them.
If everyone doesn't like them...maybe you could do something to improve it.

Why push back powersets when they're better than people believe?
Because people believe that those powersets are not not as good as the other powersets or because they've actually looked at the numbers and run tests to determine which powerset deals the most damage, has the best mitigation, is cheapest/easiest to soft-cap defence on, etc, etc.

To some people, the numbers are more important than the concept.

Fear of the unknown?
No.
Well, almost certainly not.
Some powersets are simply better in certain aspects than others.
Electrical blast deals less damage than firey blast, for example.
It doesn't mean you can't be effective with any powerset.
Just not as effective in certain aspects as other powersets.

Sharks only use Dvorak keyboards, so they can't follow your WASD.

ZOMG!

Yes, things have changed.

As far as I know there's still around the same number of lesbian futa aliens in Pocket D as there were before. I should probably take a census just to be certain, ask a few questions, pants a few people, etc.

PvP is probably harder to find as it was before, though I haven't really been looking apart from the regular sessions that one of the villain groups I'm in does.

AE isn't mostly used for farms, since we're currently in-between the last farm getting fixed and the next one being discovered. Though thinking about it, the most recent farm wasn't nearly as farmy as the earlier ones so we might be getting to the end of AE farms that are better than particular, normal missions.

If I do find out that there aren't enough lesbian futa alien catgirl zombies for you, I'll try to fix the problem. Perhaps a thugs mastermind with a special note in their bio: ((All my minions are the same as me. Especially the Gang War posse ))

Holy crap! I did not know this. I'd never even suspected.

You just blew my mind!