He's a big 19 year old defenseman, I'll wait until he's 22.
Same with Ratcliffe and his first AHL season, I'll wait a couple years until he fills out.
A lot of big players take longer to mature, as long as there is contract space and no cap implications, what's the big deal?
People want to gamble on undersized players with skill, well, most of them don't work out, you only remember the ones that do.
Same with big players with some modicum of skating ability.
Flyers have been drafting lots of skilled lottery tickets (Kase, Kalynuk, etc), so they drafted a few big gambles?
The odds odds of a player lasting for 400+ NHL games (i.e. a starting player) is:
21% from picks 31-50, 15% from picks 51-100, and about 7% for the rest of the draft.
So they're all crap shots after the 1st rd (which is why you should rarely trade 1st rd picks).