Mord ult should be dodgable,

You can QSS his ult. It is not meant to be dodgeable

It is. Walk into a bush as he casts it BAM its on CD. Play smarter and complain less about champs that offer actual counterplay.

QSS, it can be wind walled apparently, his ult is stopped by a lot of things

You can see it, and "dodge" it with any untargetable/invisibility effect.

Can't Dodge Zed's or yasuo's or Twitch's, or Garen's, or ahri's or cait's, or Diana's, or... You get the idea.

Any champ with a move that lets them become untargetable for a period of time can actually dodge the ult.

That list includes:

Then there are champs which temporarily blink out of the game altogether with specific moves like:

Champs with with on demand spellshields:

And of course who can eat an orange and escape as well as who can riposte it.

Other than that zhonyas can buy you some time, qss lets you escape, and even without either there are options to evade him in the zone. CCing him is still effective, as is mobility. He's a bit overtuned atm but there are plenty of options to handle him if you really want to put in the effort to do so.

Morde's ult is dodge-able, if you build a QSS.

If they make it dodgeable then they need to remove the QSS interaction.