As for grilling without pressing, during the eighties okonomiyaki was recognized as a specialty and the famous shops were introduced on TV and so on and thus the way of cooking 'it is better not to press' seems to have been regarded as orthodox.
圧縮しない焼き方は80年代にお好み焼きが名物として認知され、有名店がテレビなどで紹介されるようになったことで「圧縮しない方がよい」という焼き方が正統とされたようである。