My boat may not be considered a trawler, but IMO it is more trawler like than a traditional sportfisher. It is a Mikelson Nomad, built semi-custom to my specs, which were focused on making it tan excellent long range sportfisher.
Whether a trawler, or any other boat, is good for fishing depends in part on the species sought. For example, tournament marlin fishing requires a very fast boat and a tower for spotting fish. My boat is not fast enough (I typically travel at 8.5 - 10 knots, max cruise is 16 -17 (burning a ton of fuel) and max speed is 19 - 20).
My favorite target is offshore tuna, and the boat is well set up for that. 30 rod holders in the cockpit (not counting those mounted in the transom and gunnel), very large bait tanks in the cockpit, plus a smaller one on the bow, 800 pound/day ice maker to care for the fish, large self-bailing cockpit, the swim platform is integral to the hull and the stern has a reverse angle so backing down is a breeze, although the cockpit is about 12" above waterline, the swimplatform is only a few inches above, so it is really easy to get to a hooked fish if need be. The fishfinding electronics includes scanning sonar, which really helps when trolling -- if fish are spotted 300 or 400 feet off to one side or the other, a simple course change takes my spread right past them -- often results in hookups that would not have happened otherwise. And there is a tower for spotting breaking fish, etc. There are not supports or other obstructions that have to be worked around when chasing a fish around the boat. And with 2300 gallons of fuel, averaging better than 1 to one, even accounting for genset use (which is on 24/7), we have the ability to go loooong.
So, I think it is fair to say that at least some trawlers can excel as fishing platforms.
So, to answer your question,