It has nothing to do with wanting a cheesy ending, although, what's wrong with that anyway? I'd say an ending where the hero dies is almost as cheesy or cliche.
It has to do with making sense, the Mehem mod with very high EMS that would have made sense.
If that's what it is about, then there's nothing wrong with that, its just a personal preference. I'm simply pointing out that justifying use of MEHEM on the grounds that the real endings don't give you enough control or choice makes literally no sense, since MEHEM has even less choice than the real endings. If your motivation is shoring up the plotholes introduced by the whole Citadel/starchild sequence, that's a different story, and at least makes sense.
'A choice with only one option isn't a choice' , that is correct, but that's not what this is about. This is about the fact that that choice was never an option, while it should have been. The whole of Mass Effect 3 revolves around that choice being there if you put in the effort and in the end you get a 'thanks for trying but we want a deep ending that's based on horrible story telling and ridiculous notions, so deal with it'.
The series gave you at least the impression that choice was important to some degree, but in the end you didn't really have any choice.
Ok, but clearly you do have choice. The three ending choices are fairly different, and the difference between the high EMS and low EMS endings reflects the choices you've made throughout the trilogy (even more so in the EC where you see baby krogan if you've cured the genophage, geth and quarians working together if you resolved the conflict, etc etc) is fairly significant as well- given that Shepard can live or die, your teammates can live or die, Earth can be preserved or destroyed, and the Reapers can be preserved or destroyed, it just isn't credible to claim that you have no choice. Maybe you don't think its enough, but clearly you have a fair amount of control. The only thing missing is the "happy ever after" sort of ending- on that count, you're right, it isn't even really an option (although the high-EMS Destroy ending comes fairly close). But this seems narrow minded to say that the endings didn't give you any choice, when all you mean is that one very specific set of outcomes wasn't among the choices you do have.
And, as I've said already on this thread, not having a perfect happy ending among the options is both realistic and plausible, and consistent with the rest of the series, where it is a recurring theme that victory requires sacrifice and loss. So maybe you are personally disappointed because you wanted everyone to live happily ever after, but I don't see how you can objectively criticize the game simply because the writers didn't include a cookie-cutter perfect ending among the choices you have at the end.