The real solution might be would be to open up to source for the UI.
That would be really great, if they can do that with their business model.
They have already open sourced the JavaScript code for
RPG Maker MV CoreScript (i.e.: the Javascript that runs the games created by RPG Maker MV) so they might be willing to entertain open sourcing the editor also.
- However, from reading the boards --- I get the feeling the real issue with speed is more with RPG Maker MV CoreScript & should be what is fixed before the editor.
- Therefore, it makes sense to open source that first (which they did).
- It appears to be, the response from the community, was underwhelming to their opening sourcing this.
- Thus until they get a better response to this -- I suspect it does not make sense to Open Source the editor.
I would also imagine whether they can open source the UI depends on what their business model is. I don't think it's selling RPG Maker MV as their main income stream (which they could still do); but I imagine it is selling the whole working package together (including support, customer relations, reputation, their connections with other vendors) and also especially including all the resource packs.
On the other hand there is real risk someone could take the open source editor & make a clone of RPG Maker MV

... tough decision they have ...
But yes, one way or another, I would love to see the editor improved. Still -- for what it does (easy to use by non programmers) -- I think it already does a great job.
Looking at how they are going to do the editor in
Visual Novel Maker:
"Perhaps even more interesting than the Script Editor is the Extensions Editor. This is something new to Visual Novel Maker that wasn’t found in RPG Maker; it allows you to actually fiddle around with how the editor works, either by customising its existing features or adding new ones. This helps get around the issues that RPG Maker had with plugins, which often had to rely on peculiar workarounds such as “notetags” — parameters stored in comment fields for maps, characters, enemies and items — to pass information to the new code. With the addition of this Extensions feature, anyone who creates a plugin for Visual Novel Maker games can also add interface elements to the editor itself. Pretty cool."
Then applying the same concepts to the RPG Maker MV editor is probably quite sufficient & no need to open source it. Hopefully that is their plan
Edit History:
2017-11-16 1:00 PM UTC: Added section on low response to open sourcing the JavaScript engine & fixed a few spelling errors.
2017-11-17 1:15 PM UTC: Added section on the editor in
Visual Novel Maker.