I think one of the thing hurting low level play is that many players are trying to improve the 50's right now with the incarnate system.
That being said what time are you playing.
Generally, yes. There are a lot of reasons people play blueside more, but the end result is less population on red. This isn't so big a deal these days as rogues & vigilantes have access to just about every zone. If you are desperate for a team and no one's around the Isles you can always check out Atlas or Talos.
Also, due to the attention the weekly Strike/Task Force has attracted, lots of people are gathering in whatever zone has the SF/TF of the week, as Dissolution pointed out. This week has seen a lot of people in the Rikti War Zone.
Oops, I did it didn't I? I gave you a bit of nothing you asked about. Sorry as Thunder said yes blue side most often has more players, but even those numbers my be down because of the incarnate stuff.
Sorry, I didst answer the question asked 
Hey all, I just made my first new character in a long while. I've been playing my upper level guys for the past month or so after taking a break from the game for a bit, so I made a Praetorian controller, and decided to go to the Isles. At level 24 now, there really aren't many people around to team with at all. There are people scattered about, but the team that I was able to find was at level 40, and really not very good.
I don't have a Supergroup right now due to my break from the game, so until I find a good one it's PUGs. Will I have the same problem if I switch to a Hero, or are more people playing blue side at lower levels?
@Bengal Fist - Freedom - Authority SG
Bengal Fist (SS/EA) - Thirt3en (Time/Elec) - Aussi (Elec/Shield) - Potamoi (Water/Time) - Parkr (Staff/Ela)