Been playing out since 1968 and "Boomy" was never considered good, but there was certainly more of it back then, but this was certainly not always the case. Had some refridge rigs, including an Acoustic 360, that actually sounded great, and were not boomy in and of themselves, but I would never want to lug those around again. The "boom" was caused more by the inferior front of house PA systems we used back then. Vocal and stage mics picking up the low frequencies and things not being eq'ed properly were a huge culprit.
I started playing out in the mid 60s. Never saw FOH PA systems until the 70s. That is when boom became noticeable to me.