Disclaimer: I have played momentum since level 98 for levelling, M+ and raids and enjoyed it.
I completely disagree with what you've said there, and I think it's a slightly inflammatory attitude to bring to the forums - telling people to go and reroll. Momentum is an interesting talent which creates a unique playstyle, but it is absolutely not the only feature of Havoc which sets it apart.
The baseline mobility of the class is, for me, what really drew me in and what I enjoyed most before raids started, and ultimately the enjoyment that I gained from this caused me to re-roll from my mage (which I had mained since Vanilla) to DH. Not only this, but there is a unique feel to Metamorphosis, (playstyle and visual) and the class is exceptional in solo content. There is obviously also the class fantasy overall, which goes without saying...
I've had a lot of fun trying to perfect momentum usage in raids, but I have to say it has an obvious downside in that it detracts from my mobility in a raid. As soon as a *target random player* or *target random area* or *soak mechanic X* mechanic requires you to move, you suddenly find that you have 0 charges of FR and have to run, just like any other melee. If anything, for me, using momentum has detracted from what I love most about the class - the exceptional mobility. I will likely try Nemesis in ST in 7.1.5 and keep FR at 1 charge to try to regain that lost mobility.
I would go so far as to throw your point right back at you, and say that if you want to blow all of your mobility for a dps increase, maybe you should go and play another melee class which doesn't have the baseline mobility at all? Frost DK might be perfect for you
[yes this is tongue in cheek, as per my first point about telling others to reroll...]