Wit's End needs some more work than just reducing price

Imagine I'm high-dps on-hitter. Stacking MR doesn't matter for me, as magic damage often comes in burst. On-hit and attack speed aren't too special either, so most likely you build it for MR reduction. But than again, if I'm hitting a tank 25 reduction will barely matter, and if I'm hitting a squishy, after 5 attacks it's most likely dead anyways. Also I quite likely

Now imagine I'm tanky on-hitter. I quite likely don't need 70 more MR, as there are more important MR items like banshees or SV or portal, and stacking too much MR on a tank is usually a waste. The rest of the logic applies as well.

Literally only champion Wit's is actually a worthwhile build on is WW, as his ult will quickly apply 5 stacks, for devastating R+Q combo, but he is getting reworked.

Reducing price will make it stronger, obviously, but it will still be early game item that doesn't really have place in a full build - just like now, you can rush Wit's End to easily beat your lane opponent, but soon after laning phase you are going to regret it. There is a reason why all early game oriented items in this game like or were given upgrades - nobody ever bought them, as they were only good for annoying your lane opponent. I.e. a Kayle could rush Wit's End to annoy enemy Diana even more, but as soon as she completes 2nd item, she is going to regret not getting Nashor's.

TL;DR Reducing price on Wit's End won't make it a worthwhile build.