Force does reduces DPS but people kinda forget that it's balanced just like paralysis weapons in Monster Hunter are. You chip in for the next stun phase, which is nearly always a DPS gain for the whole party. Counters are nice but it's preferable if the gun UQ Doll boss sits down instead of jumping around the place and he isn't all that nice to counter for melee classes. Similarly downs open up a weakpoint on the dragon boss which is yet another reason not to underestimate these.
It's not that great of a solo class but that's just how the balancing works where it's meant partially for support. I won't be surprised if an 8/8 Fo MPA for either UQ would end up with constant elemental downs on the boss, at which point giving Force more damage without doing something to lessen the elemental downs could result in it being both braindead and optimal setup. There will probably need to be some balancing overall, but Force is supposed to have lower DPS than melee classes just because melee classes lose a lot of uptime on jumping enemies and only at most bring physical downs which don't seem remotely as potent per person.
I would also advise against comparing DS Fighter 29s since that's already getting nerfed and Sega is trying to save face saying it's a bug. The lowest counter classes go on Bujin is about 37-38s I think, which is basically Sword/Knuckle/Partizan. This is somewhat lopsided but that's a super counter heavy solo content, and even in an MPA Bujin only one person will get the perfect aggro that lets them use all that bonus DPS.