I played a game against a not so competitive Space Marine army with some allied robots. I absolutely wanted to try something different and due to the fact that I have enough tanks I wrote a list without a single Battlesuit.
Well... it really underperformed. The first problem was finding cover for all those tanks. Devilfishs were kept back for counter attacking. And so was my half fluted with big tanks. Against enemy fire I had often to jink or I lost the armor quick. Therefore my shooting phase went from bad to terrible. Tanks can't hold up with the rate of fire from battlesuits. And even without that they are immun to jink. Either they have their own cover save or a good invul save. Tanks are limited to movement too.
Relying nearly only on the FB from Piranhas was something different too. In other games I have a squad of 3 dFB crisis. Those Crisis melt nearly everything. Again the piranha struggled.
Only taking tanks wasn't a good idea. The other way around, taking no tanks, function very good. Tanks have too much problems against nearly everything in comparison to suits.
What would help would be the return of the "shoot as if you where a fast vehicle"- system. Also the ioncannon needs a ap2 upgrade. Maybe overall a point cost reduction.
I love tanks, too. The Hammerhead was once my most loved model. Make tanks great again.