There are “modders” and “modders”, I suppose you mean module builders. Module builders are creating single player modules or are working on persistent world.
Term modders is not used much around here, although I think few peoples, myself including fit under this term. We are making overrides or hakpacks that are changing ruleset. Though it is easy to put us under another category.
And then there are custom content creators, those who make any kind of custom content to be used by module builders.
Thats a small introduction…
As for NWN:EE, most module builders would be probably satisfied with 1.75 - the new features are awesome. Same as well most module builders are not using anything extra which would be incompatible with NWN:EE and thus will be able to open module and work on it without any issues.
For custom content creators there is probably no drawback, nwn:ee is very rich for new features especially for working with models and textures.
Unfortunately, module builders working on persistent worlds usually use lot of extra functionalities. Same goes for modders and thus the transition to nwn:ee is either not even an option due to the lack of technologies or peoples who would do that work.
Personally, while I was, and still am, supporting nwn:ee with all I can, it doesn’t offer even 10% of what my nwnx plugin for 1.69 allows to do. And I enjoy making ruleset packages using nwnx plugins and nwnx plugins myself. Unfortunately, the situation about nwnx is really bad for me - no symbols, no windows support (I am not interested in docker sorry) and mainly - no support for NWNCX (which is what I am modding for mainly these days - see PRC Lite).
Anyway, it seems nwn:ee brought a lot of new players into NWN, this is easy to see at steam. So if you can you should transition to NWN:EE as you get more downloads, more comments, more feedback…