To make this somewhat relevant to the OP...
While Felon and BkMamba make valid pionts, I haven't really seen this "sameness" issue cause any problems in my group's HERO campaigns. In actual play terms, we're all creating our PCs with the same amount of points, yet still keep our special-effects niche: power armor guy (me), supermage, brick, alien/robot, gunslinger, etc. Certain PCs fare better against certain foes, tactical decisions are made, and much enjoyable mayhem ensues.
We all know we're playing within campaign guidelines where Active Points are in range X and typical Def is Y, and we build PCs to be effective in that zone... whether that's via sheer amount of dice, or Advantages, or Find Weakness, or whatever.
Whether M&M (or any other SHRPG) does this better or worse, I can't say definitively, as I don't play other SHRPGs nearly as much. All I can say is that HERO works for us with the same caveats I see in other systems I play (e.g., D&D): setting appropriate challenges, good GM-player communication, etc.