What is the purpose of Flash then?
And you have to understand how annoying Mord is for most people. If your team has one weak link (which happens a LOT in solo queue) who overextends in a team fight, Mord simply has to ult them, they die, the other team now has two supercharged champs instead of one mediocre champ.
edit: Talk about good timing! I was typing up this reply while in queue and was interrupted by champ select. Here is that game:
http://img180.imageshack.us/img180/6430/mord.png
I had solo top vs. Mord and Yi (they had no jungler). Mord walked in front of the minion waves, and I could not do ANYTHING. Fortunately they didn't know how to last hit, and I got a high creep score. But I couldn't approach them at all. How is it possible to out-harass someone who casts a single spell and is then invincible for the rest of the creep wave? Not to mention Mords almost always get regrowth pendant first and thus gain health quickly (and can cast spells infinitely).
A team fight happened up top after a while. Our Xin was fond of going rambo. He was the "weak link" I talked about earlier. Mord would ult him, I would bulwark him but it wasn't enough, he would die, and their team would have a supercharged Xin who would tank the tower while the rest of them fought. A fight at bottom lane ended with me and Mord alive. Xin's ghost alone took the tower from 1/3 health to dead, while me and the tower were hitting it the entire time. That is the definition of bull****.
I know it must be nice to play at the level where nobody does stupid ****, people buy QSS'es, and Mord is shut down by your team. I recently escaped from Elo hell (I was 800-1000 for about 100 games, then got a winning streak about 25 games ago and am now around 1250 and rising) so hopefully I'll get there someday. But he is definitely a pubstomp hero on the level of Twitch and it's REALLY unfun to play against. I'm all for making him viable at high level play, but it must be done wihtout buffing him to the point of brokenness at mid and low level play.