I can see where the development of mod tools could be a drain of resources and money for a company.
But if the response to Bioware's devoting time and money to such, it's a wise investment, IMHO. IIRC, a few of the really good modders for NWN eventually got onto Bioware's payroll either as consultants, beta testers, or designers. There were also a few of the design techniques used that made their way into the company's future releases.

I buy Bioware products sight unseen without even reading reviews because I know they produce good games, have excellent customer support and even if I'm less than overjoyed with the original release, I'll find plenty of mods later that satisfy me.

That is DLC people would pay a deal to get, even if released one type of editor at a time.
I'd hate to see that and I think it's totally unnecessary to generate funds, in the long run.