Just that Sigil is going to have to get MUCH easier to use at some point - I'm sure WoTC is not going for a product that only the most hardcore users will use.
I will point out here that this particular issue has killed countless software projects.
I.e. "We can make a tool that's powerful enough to be worth using, but we can't make it sufficiently usable to a non-hardcore user".
One of the products we use at work, it's incredible but is stuck in that trap, design-wise. It's very powerful, but they've been trying to make it more accessible for years, and just have never succeeded in finding a way to do that which isn't just limiting functionality pretty hard, which then begs the question, why even use this particular product? So despite first-mover advantage, it remains less popular than it should be.
I'd personally suggest all the tools I'm aware of which are analogous to (but admittedly not the same as) the 3D VTT are fairly challenging to use.
None of this is to say they shouldn't try. They should.
But you might need some kind of truly novel thought or approach in terms of UI in order to make this genuinely accessible.
It's alpha. What are you expecting?
The problem is, if something is hard-to-use in alpha, it's often because, fundamentally, the developers don't have any big ideas on how to make it easier to use. Not always. Some software does genuinely become much easier to use as it goes on - but my personal experience (which is just that and nothing more), is that the opposite is more often true. Alpha is not feature-complete, generally, and doesn't have the detailed/fiddly features that might be added later on, to meet requirements, so if it's already hard-to-use, you can't necessarily expect that to vastly improve. The UI will probably get refined, but refining a UI won't make "clunky" or "hard-to-use" into "accessible" or "friendly", it'll just make it slightly less painful.