The problem is that certain audience members just expected to have their fan service brain centres massaged again, since that’s what a lot of what TFA and Rogue One offered. SW was back, and it was important. They were important as fans. But since TLJ didn’t end with Luke killing 400 dudes with a green lightsaber nobody cheered.
I haven’t seen a lot of criticisms suggesting Luke should’ve been a one-Jedi army; he wasn’t in the OT (although he came close in the escape from Jabba’s barge).
TFA and TLJ are both mediocre Star Wars movies (in my opinion) for a variety of reasons that have nothing to do with fan service (whether it’s too much in the former or a complete lack of in the latter).