Maybe it's technically not illegal, or maybe there's some election law that they violated. But knowingly receiving dirt that you know came from the Russian government sounds like collusion. Colluding with a known hostile actor in the world isn't a great idea, even if some of it wasn't illegal.

In Clinton's case, she didn't know the info came from a British spy, so I wouldn't call it collusion.

It's the sheer volume of 'coincidences' of contacts with Russia that show a concerted effort by Russia to influence the election. Team Trump was happy to receive the help. The fact that they keep lying about meetings, contacts, etc. makes a lot of people wonder what is there to hide if everything was above board.

I'm curious as to whether Mueller thinks those items represent anything illegal. If he says no, I'm okay with that. He knows the law better than me. Time will tell what he thinks.