It's probably because I didn't play soccer growing up so I don't have the muscle memory (though have gotten passable playing with my kids!), but I've always said PKs in soccer and game winning FG attempts are the most pressure filled moments in sports.
Reasons for PKs:
-PKs on average have a very high success rate, something like 80%. The number is high enough that the fans expect you to make them just about every time so if you make it, you were supposed to, if you miss you completely choked.
-It's literally just you and the keeper all alone one on one with 60,000+ fans watching you play mind games trying to out think them, completely different mindset than the 120 minutes that were just played
-A miss can dramatically shift your teams chances and overall mindset (though as we saw today in both PKs, they can be recovered from)
-A high profile miss is replayed for years and you are forever associated with it
Clutch FG kicks are similar, except literally your only job on the field is to make those kicks and what you do can validate or erase what 50+ teammates have done all game to get you in that position. And even worse for FG kicks several things can go wrong but if that kick is attempted and missed, the blame goes squarely to the kicker even if the snapper or holder screwed something up (Laces out Dan).
I could never do either of those things for a living.