And how is Noel Gallagher any more of a musician than Ashcroft? They're both fairly limited in their guitar skills.
One is much more limited that the other. By limited, I mean laughably play-in-a day limited.
Anyone who has ever picked up a guitar would know the difference between NG and Richard.
Go back and watch Champagne Supernova live in 1998 from the Be Here Now tour, it stretches out to about ten minutes, Noel in total control of the whole thing pushing the solo forward.
Richard learned the basis chords back in the mid-1990s, and hasn't progressed from there on. He is exactly as good as he was when he first learned the chords. Look at something like They don't Own me, three chords, round and round, it's begging for a change and he just plods on for 6 minutes.
Yup, RA's guitar playing is just bland and monotonous. He literally just strums the same 4 chords over and over. And as you said, his playing is no different now that when he first learned.
He doesn't play any notes while he strums, attempting to replicate other instruments from the song. A good acoustic track should be an attempt of a full rendition of the song, played on one instrument to the best of the player's ability.
Richard just lazily plays his guitar as if he would with a full band backing him, but they're not there and he doesn't do anything to fill that void to make the songs interesting in the slightest.