A smaller hull likely doesn't have the space for the power plants you need for the big ass gun you want to fire. Unless you use torpedos, but they have other issues.
The biggest issue I always had with space combat in Star Trek is that the rules and even most specs of the weapons are unclear. Combat happens at point blank range with other ships only a couple hundred meters away, which is odd. The only hard number on the range of fire control, phasers and torpedos I personally know is 10,000 meters. That's the range you have in Starfleet Academy, the 1997 space flight simulator. Quite good game/visual novel, actually. But then again 10 km is nothing, in partcular when you know that WW2 era capital ships had up to 30 km maximum effective firing range with their main guns and 5-8 km with the secondaries. It is even less than nothing when you realise: oh, you're in space and you're using directed energy weapons most of the time.
I can imagine that with FTL-sensors in use by everyone phasers have an effective range of a least one or two lightminutes; that would be roughly 18-38 million km. And with 23rd, 24th century tech there is also very little dispersion of the beam, so the punch over longer ranges should be very consistent. I can understand why the writers went with very short ranged fights, so that the audience can see what's going on and who's shooting what and so on. Even in nu-Trek where CGI has replaced models they default back to close quarter fights that at most happen at less than a thousand km between the fleets and no one is really maneuvering, at all.
LoGH and the Expanse - for all their other flaws they have - have better space combat. In case of the former, combat happens over tens of thousands of miles at the very least. The fleets are large enough they occupy a whole lot of space and coordination is difficult, often impossible to due massive electronic warfare. They relay orders with couriers in shuttles, lol. And because of all of that, both sides have ships where almost all weapons are concentrated at the usually heavily armored bow. A good portion of the fleet combat revolves around trying to outmaneuver or encircle the enemy fleet to hit them from a direction where their weapons aren't pointing at. The Expanse has CIWS to shoot down incoming missiles and torpedos, something that should be possible to accomplish with phasers. Some of the weapons they have can't even be used at very close range (railguns and virtually all missiles). Hell, even Star Wars has at times a better grip on these things...