One thing that seems to be forgotten here is that Come and Get It is a very particular type of forced movement. Most of those forced movement powers that require some sort of a roll allow you do something like, say, push 3, or slide 1, etc.. Basically, you have some choice in where the enemy goes (think about a Wizard using Thunderwave to get enemies away from him). This increases the utility of that forced movement compared to Come and Get It, because now you have a lot of tactical options in how to use that movement and where to place enemies.
Come and Get It, on the other hand, works in one direction: towards the Fighter (also key it only works if the enemy will end up adjacent to the Fighter). If the Fighter pulls in 8 enemies and doesn't manage to kill any with the attack, then guess what? The Fighter just surrounded himself with 8 enemies. This means that the Fighter is now unable to move (all adjacent squares are occupied by enemies) and he is being flanked by 8 enemies. This is not what you would call a "good" situation tactically, and it gives the DM plenty of ways to lay the hurt on the Fighter here. Basically, Come and Get It's forced movement can often result in situations where the Fighter is surrounded by enemies who have naturally been set up into flanking positions. Sure, this sets him up to use stuff like an auto-damage stance or Sweeping Blow...but it also sets the monsters up for flanking bonuses all around and a simple shift+charge will get them out of the whole situation (the Fighter can only punish the first person to shift, the rest have a free pass...although they're probably now marked, which does mean they're at a -2 to attack) if need be.
Basically, while Come and Get It is an excellent power and a lot of Fighters use it, but I think some of you are looking at it without really thinking about the tactical situation. You can't compare it directly to most forced movement powers because it doesn't work like most of them. Yes, it gives a form of battlefield control, but it doesn't allow for the fine grained sort of movement control that a true controller has. It can't be used defensively at all (unless you have some kind of power where you actually become stronger the more times you're flanked) and even it's offensive use is a bit of a gamble by basically saying "Everyone attack me!!!!".
Now, there's a good explanation for why so many Fighters take this power. Basically, it's cool...just the whole idea of a massive whirlwind style, vacu-suck attack that pulls all these guys to you is really awesome. Add to that the fact that I think a lot of Fighters share a similar attitude about taking on impossible odds to protect the party, which Come and Get It does by sucking practically everyone is a 3x3 area directly to you, and it's just a natural fit. The power practically dares you to use it take on as many guys as possible, and a lot of Fighters (myself included) like that feeling.