So your endeavour is replaced by others. Your logic could easily be used to rail against using calculators rather than slide rules or to rail against all Lego in favor of Erector sets, etc.
As others have stated, Lego was in trouble before adopting the franchise sets. Would it be better if Lego was 'pure,' but out of business? It's not like they removed the ability to do what you're talking about, they just added new things. You could easily limit yourself, or your children, from using the new things.
I don't know whether I ever came up with a decent solution back then, but I do know that trying to come up with one was an excellent exercise, one that I probably would never have embarked on if I'd had the pieces they make today.
edit: grammar fix