Yep. As big a dick as Tom was post reunion, I still believe he wrote better music for blink. Not that it was anywhere near the quality of peak blink, but he still had a number of good moments on both records.
Mark, however, seemed to totally phone it in apart from Kaleidoscope and HAG, where the quality increases because of how angry he seems to be on it. That was him writing with a sense of purpose, and both were good. On other tunes though, his writing is just so generic and uninspired. Nothing really interesting, just the same power chords and that awful bass heavy tone that he has on his guitar.
As you said, he probably knows it which is why he doesn't write many songs as he is afraid of being shit.