Um, no. People have been defensive in this game without projectiles. Why nerf projectile damage? Might as well nerf everyone else, then. Besides, shielding projectiles in this game causes them to stale, a feature not present in previous games.
As for online, I blame GSP. People are more focused on maintaining their points, rather than learning to deal with match-ups.
Why NOT nerf projectile damage? Are they contributing anything to the game other than being incredibly annoying? I realize that you have samus as your main for all 6 games, so we may just disagree here, but my personal view on this is that the most common complaint about this game is projectiles. Like you can't be telling me that Wolf laser or Pichu Jolt are reasonable in the % that they put out in addition to hit stun, and being zero risk. They could halve or even remove the damage of both and they would still be incredible tools.
I think if traditional powershielding made a return, they wouldn't be quite as frustrating to deal with. But powershielding brings about its own issues, considering you could act immediately after performing one and completely ignore shield damage and shieldstun, and it wasn't restricted to projectiles hitting your shield, either. Overly defensive play could make a return, as powershielding was super easy to pull off.
With parrying, which is a little harder to pull off successfully, the defensive play isn't as attractive. But they have kept projectile strength very high, as well. Parrying projectiles offers little reward to the risk you put yourself into, especially against characters like Pichu who can chase their projectiles. Parrying projectiles does nothing to the attacker, so they're free to punish as they see fit regardless of whether you parry or regular shield, if the attack causes enough shieldstun. Parrying has actually buffed projectiles in a way, because you have no quick way of negating them, unless your character has a counter, reflector, or the ability to absorb...ohwait, how many members of the cast can do this now? Yeah, a lot of them. Maybe not intuitive to counter every little Luigi fireball or something, but strong stuff can still be negated.
So, I don't think projectiles in general should be nerfed. Characters centralized around their projectile play could become unviable this way. Most of the heavy projectile users have some glaring weaknesses already. To convert some characters into primarily CQC fighters would take a complete overhaul of them, and ruin the fun for people who like projectiles. Then you have the argument of nerfing individual projectiles....which is a whole other ballgame of a discussion, because then you're talking about nerfing characters, not projectiles as a whole.
My solution is to not pick FD against them, ever, and just learn to get around it. I dunno how many times I've just jumped over Samus's charge shot and beaten the snot out of her now.