Neonchameleon
Legend
But I also run games in which other humans/demi-humans are frequent antagonists. If they're running into opposition fighters, it makes sense that some would be using powers like Come and Get It. If the PCs can do it as part of their fighting repertoire, why shouldn't NPC fighters with similar styles? Is that discouraged in 4e for some reason? Why?
It's simply not encouraged as PCs and NPCs don't work the same way.
As for NPC fighters using CAGI, it's simple maths. PCs are considered every bit as exceptional in 4e as they were in AD&D when the majority of humanoids were level 0. Very few of them are going to have non at-will PC type powers - and those that do will be elites, and almost all signature bad guys (whether the BBEG or a notable lieutenant). An NPC that signature only IME crops up every few levels. There were 25 separate PC classes even pre-essentials so using a fighter as a base is comparatively rare (even accounting for weighting I'd expect Warlocks, Blackguards, and Wizards to all outnumber fighters at this level of distinction). Then that named bad guy needs a specific level 7 (or level 23) encounter power. There are four other encounter powers at that level in the PHB - and about a further dozen in other books.
Now if a serious adversary were to have CAGI, it would be brown underwear time for the PCs - but I doubt they'd object, even pre-errata. It would either be the major villain or the villain's chief enforcer, and part of an epic fight. It would probably only happen once in an entire adventuring career, and be a defining point of a battle with a greatly feared adversary.
On the other hand if Random Thug #2 had CAGI, the players would probably object. In much they same way they would if random thugs started throwing around Hold Person or Glitterdust.