The explosive spam in this game is really a problem I think but the design philosophy of this game seems to be, to make everything more "easy".
If you look at the accuracy of the weapons, they are really easy to control the recoil even over long distances without bursting. Every vehicle needs explosive ammunition, just to make sure, that they have not to hit with their weapons, everything needs an area effect. Additional, more explosives have been introduced throughout the season.
So for everyone, it should be easy to kill the opponent, the tools are doing the work, not the player.
All this mindset just resulted in camping tanks (Thor or AA) with the trophy system. They were nearly invincible, so the problem is not Irish, it is the gameplay itself (or in this case the tanks) but the fastest and more easy solution was to nerf Irish, because nobody picked him for his abilities in the open, more for defending their own tanks. Nerfing the tanks would probably bring other problems, tanks too weak against infantry, or air would be superior...
I don't like the change and the explanation, he is one of the least picked character, so we nerf him, makes no sense, without giving him something else... But I can understand, why you maybe nerf him, there were situations, his ability was way too strong and gave too little options of counterplay, still it is disappointing, because nothing will be done, to increase his popularity, the only thing what it happening, everybody is running around with Falk, McKay or Boris (only because of rocket launcher), because all other specialists are just awfully bad in comparison.
That is no proper balancing but I think, Dice gave up on this front. Otherwise, there is no explanation for Rao, Boris, Casper, Angel, Crawford or Dozer without any love in the latest patches. All are just not competitive and / or boring and you have a huge disadvantage, if you pick any of them.