I probably saw it before, but only now I really took note of it... Why aren't Clearance Items not included when an Artist's shop goes on sale?

Happened today, as Xtrart-3d's store holds quite a few G3F items that I have on my wishlist, so at first I was like "Wow, 70% off.. that's great..." but then I was "Wait, what? Clearance items still only 35% off and therefor double the price of a reduced new item?!??!?"

I can understand why coupons won't work on clearance items... but you're really missing a chance to generate sales here, by not giving them the same price reduction(s) the rest of the shop gets...