What lies behind some relatively recent additions to our davening
I've seen a suggestion that Psalm 30 is just a mistake in nusah ashkenaz, based on confusion with Sephardic minhag (which may or may not be from the Arizal.)
A distinction also must be drawn between innovations and popularizations; e.g. Eishes Chayil on Friday night was one community's minhag, and the school of the Arizal popularized it. Machzor Vitri suggests saying pitum haketores at mincha, but that's not who the Rema and Mishnah Berurah quote. Gradually, more people added hodu to pesukei d'zimra, a minhag Abudarham dismisses.