If you need something, sending in a suggestion is always a great idea, so I'd encourage you to do that.
New features get prioritized mainly by the balance between how many people want them, how easy/hard they are to do,and whether they might have a catalytic effect on making other parts of the system more effective.
Everything starts with requests/suggestions: It's important to "vote" even if you only send in a short request. Those add up.
But if something is really important to you, it can be worth it to make an extra effort beyond a short note. More effective lobbying can help if only one or two people ask for something.
Visit the Suggestions page and read it for overall tips. What you're asking for is basically a new format, so check out the advice in the New Formats section of that page. When relatively few people ask for something new, it helps if they provide the supporting data that makes it easier to implement, such as providing a source that gives an authoritative description of the format, citing an organization that publishes a very large amount of useful data in that format, and so on.
For something like a vector tileserver version of ArcGIS REST, that seems to be a niche thing at the present time, so my guess is it would gain priority if a) lots of people were using it or b) there emerged some big collection of data being served in that format. Of course, pretty much every accepted standard started out in the beginning as a niche thing, so there's a balance between waiting for something to take off and being among the first to support something new that looks like it will be popular.
Suggestions help Manifold to get that balance right, so don't hesitate to vote. At a minimum, take a minute or two to send in a short request. You can always add to that later if you want.