It's a reasonable estimate. In other words, if 'enough' people care, then it's more practical to do so. But if it's "less than 5%" or so, as you say, it doesn't sound practical, the way you made it sound.
And then you say "0,1% is problematic" (or 0.1% or whatever you meant) when it's unreasonable on the part of Image-Line "alienating" the user base? 0 to 1% is almost nothing---it just made your stance sound less motivated (i.e. it's like you said "if it's less than 5%, people should care; heck, even if it's 0 or 1%, people should care"). Yes, they SHOULD care, but practically, would you expect that they would? About 1%?
That's Neblix's point. Blunt, but there you go.