So, on that. I agree, but I also think that there is one small change that could have dramatically improved that problem.
Here's the thing. What we are left with is the typical "Evil Overlord" problem. Sure, he's got this great plan, except that he doesn't account for the fact that ... you know ... it might not work. He could have just killed Sylvie and Loki easily and there would have never have been a need for any of this.
Imagine, however, the whole issue re-contextualized. HWR won. He won the time war. He got all the power. He could deal with Kang variants easily. He controlled time, and did whatever he wanted. But what did it actually get him? Nothing but sitting, alone, at the end of time. He had all the power, but it didn't matter. It was all meaningless.
By presenting Loki with a choice, he injected meaning back. Because Loki could choose to either kill Sylvie (and thus keep him in power, which would be entertaining if nothing else). Or Loki could end everything by letting him die (which would be entertaining, and also release him).
Or Loki could take his position, which would also free him. He had accomplished everything. He had won. He had gotten all the power. When Loki took the throne, he assumed the burden that HWR had. Which is not just entertaining, not only releases him, but is also its own kind of victory.
....but they didn't bother providing the necessary depth or information to let us see that. Just providing us a little bit more might have made it a much more complex ending. Instead, it was simplified down to "All-powerful villain concocts an overly-complex plan for no good reason, and doesn't realize it could fail." Oh well.