I think there's pros and cons to both very phonetic and very "historical" spellings that a lot of people don't think about, so I wouldn't necessarily just say "let the past be the past" and that's that. Spelling reforms should focus on the areas that people actually struggle the most with in practice, embracing common misspellings and colloquialisms without necessarily imposing them on people.

I think the last major Irish spelling reform was in 1957, and before that 1931, and these reforms drastically simplified the spellings, like ochtú used to be spelled ochtmhadh, it was that extreme a simplification. So the oddities of Irish spelling are as much a product of "historical spelling" as they were a very deliberate and careful choice by revivalists less than a century ago: it does indeed make a lot of sense to use those letter combinations in those ways when they reinforce the inflectional patterns and help people identify the dictionary forms of new words they encounter!

Edit: It seems like the current Irish orthography has some number of detractors due to dialect bias! So what seems like simplified spelling to one dialect is actually horribly un-phonetic for another. This goes to show that getting rid of silent letters isn't always the same as simplification in practice. Most Irish don't seem to mind the current standard spelling, however.