If anything, I'd make artillery deadlier, but lower its ROF and implement a scale of supply costs for ATGMs.
Have you looked at the stats for the MLRS and AUF1? if you made them any more powerful then there would be no need for conventional forces as people would just arty spam even more than ever before
And changing the ROF for arty will just mean people will either spam even more, or will drop it all together. As for ATGMS, raising supply costs won't help. If you want to prevent ATGM spams, then decrease the ROF and make it take longer to resupply [you could also lower availability since no good player needs 12 I-TOWS]. That way they maintain their tank killing capabilities and we don't go back to the heavy tank meta
PS. I think the current meta is fine as it is, I simply don't want to let your bad idea's be the only ones Alicuza and Eugen see's.
PPS. Keep up the good work Eugen!