I think it is limiting.
It really is. My typical write goes something like the following: "OK, let's write this register. Double click. Why is it not highlighting? Oh yeah, I'm in read-only. Click on Toggle Read-Only. Double-click on register. Opens for editing but not highlighted/selected. Double click again to highlight. Enter new value, and <enter>. Is it written? Doesn't seem to be working. Oh yeah, write isn't committed yet. Not in auto-write mode because we just got out of read-only and it was cleared. Choose one of the five write modes, and click.....AND there's a confirmation that you didn't just spend the last 15 seconds and 23 clicks trying to edit the register unintentionally." And then, assuming I remember to, I have to re-enable polling, but that's still two steps because I have to enter read-only and re-enable polling in two separate steps.
So a big part of this is me and that all the steps are not yet burned in to an automatic level for me, but I think even objectively, it's way too many clicks, way too many modes, and way too much caution, none of which be turned off by default. The competitive version is Click-type-enter, and it works like a charm. User-selectable confirm-to-write and read-only modes would be nice for certain applications, so long as you can leave them off by default, and not just for the current session.
Update: Did come up with one workaround -- open two identical MV's and configure one for polling and one for writing.