If that's the case, I've got a Batman team I'd like to play against you.

While certain things have given Stealth a kick in the teeth, I think it's also been given a few more tools to use. You don't actually need to be in the hindering terrain; you could always hide behind it as well. And with the advent of Special powers, a lot of characters managed to secure the ability to use Smoke Cloud as a free action, or to use it along the squares they've moved through. Move Human Torch and then have JL Batman hop into and shoot.

Are there a lot of ways to kill off hindering terrain that's printed on the map? I always prefer to rely on printed terrain rather than man-made stuff any day, it's just more consistent.

Out of curiousity, as this came up in a game recently and we weren't sure, can a TKer based by an opposing figure still use TK to move objects and friendly characters around?

For example, if Plastic Man bases Lyssa Drak on my turn, can Lyssa still use TK to fling Arkillo across the battlefield on her turn?

Yes. Lyssa isn't making a ranged combat attack, so wether or not she's based doesn't matter.
(she could even move an adjacent opposing character - though not Plastic Man, since double-based characters cannot be moved by Telekinesis - since that would be a close combat attack)

Thanks. That's the way I interpreted it after reading the PAC and rules, but this thread reminded me of that situation and I thought I'd make sure.