"Allergic" is probably not the best word, but I think that's a decent summary.

Jon is not a hard rock / heavy metal guy. He grew up idolizing Bruce, Southside Johnny and the Rolling Stones. Early in his career he looked up to and compared himself Bryan Adams and The Cars. These are singers-songwriters who made catchy tunes, but and were rock acts, but not big on guitar solos.

During the 2016 Eddie Trunk he said "we were lumped into the genre because we looked a certain way". Guitar solos were a big part of that genre so they followed the formula. And because the songs were so great that they became synonymous with the 80s hard rock scene, even if Jon himself did not identify with parts of that scene.

When you take that into account it's not that surprising that he decided to gradually move away from (focusing so much on) guitar solos, as they attempted to reinvent and commercialize their sound, and as Richie's influence in the band seemingly decreased.