Truthfully, until about XYZ at least, Team Rocket had a decent enough compromise of bumbling and competent. The problem however was that, while this made them look less pathetic against the twerps, the show's usual solution to defeating their more menacing plans was, rather than having Ash and co sweat and work a bit more to stop them and prove they could take the extra challenge, they'd have another character or dumb luck swoop in and stop them instead (Mega Meowth Madness, Coming Back Into The Cold, ALL of the episodes concerning an evolution or an ME, etc), thus the twerps still won without trying anyway. This had the bad side effect of sometimes making Team Rocket look more hard working and competent while the twerps were just lucky and hadn't proved their worth. Only Ash and his Pokemon handled a fair amount of 'not completely harmless' Team Rocket face-offs by themselves with skill and resilience (eg. Grooming Furfrou, Frenzied Factory Fiasco, the wetland two parter), the others could only handle them at their most incompetent (as in just standing there gloating and not really offering any sort of retaliation), thus like you say, not really an accomplishment. The only reason they seem more capable now is because TR have been dumbed down more and more and thus can't show them up anymore (though the odd time they convert back it still shows, the twerps are still useless against their mechs for example). This is 'cheating' in terms of writing, since the whole point is that the twerps are supposed to be getting smarter and stronger, not Team Rocket getting dumber and weaker.
Still, even with that reasoning it's not exactly a good writing method. Team Rocket is the twerps' main opponent the whole series and who they most recurrently show any display of progression and improvement against. If they fail to make the twerps look good against them (either because they are TOO weak or their method of defeat is too spurious), then they fail their role as foils to the heroes. Maybe this is why so many fans think they became superfluous this series.
I'd rather she won anyways and I don't really particularly care about that DEM crap of an argument since it happens almost all the time in every series that we've had so far anyways.
