Hernandez's drop was worse (it was a perfectly thrown ball that clanked right off his hands) but Welker's was in a bigger spot. If the Pats get a first down there then they could've run off the clock and barely given Manning any time to come back with.
I thought that was pretty funny and had understood he had a pretty good relationship with Ryan (could be wrong on that though). As I fan I prefer to see players seeming to be genuinely gutted about the loss than going partying like Gronk a few hours later.