Great for you. I don't think one could claim such stuff never happens. I also had a few interesting wars where there was a change of fortune over several years and a lot of fleet posturing, reequipping, sieges, ground wars and waiting for opportunities and raids. The issue is it only happens in a very narrow sweet spot of relative strengths and development.
I think the issue is mainly a lack of mechanics that broadens the range at which wars are interesting. Maybe to think about it militarily is also a bit narrow. EU4 can be a blast as a small border skirmish with a neighbor can escalate into a major coalition war over time and in the end you just want to forget aboutt he provinces you tried to conquer and just want it to stop without you losing anything.
Overall Stellaris needs more dynamics in how fleets clash so fleets can maintain their strength better when being outmatched (aka easier to run away and regroup), use tactics geared to a particular situation (e.g. corvettes just making a torpedo run before running for their lives in the hopes that this can destroy a few capital ships) and defenses that make conquering systems a longer and less repititve process (currently jump into system, smash starport, bomb, invade, repeat till you win). Additionally Stellaris could use more dynamics in the diplomatic area to make wars more dynamic.