Whenever I play a spellcaster, and I level up and it's time to pick/prepare new spells, I almost always avoid those with material components that have a price, since you can't just substitute them out for your spellcasting focus (i.e. ignore them like you can pretty much all other material components).
The idea that you have to keep an eye out for these very specific and very expensive items (Imprisonment seems like a particularly good example of how obscure and expensive some of these materials can get, although it is an extreme, what with it being a 9th level spell, Clairvoyance is a less extreme lower-level example) and I find this quite annoying and I just end up changing my decision of spells instead of dealing with that restriction, thereby effectively taking that spell out of the game. I'll point out that I've never asked my DM how likely I am to find the item; I just change my decision.
I want my D&D games to be about being heroes and killing dragons and such, not about shopping around for extremely obscure items just so you can do something once (if it's one of those spells that consumes it, which are the worse type of spells-with-a-material-component-with-a-price), then it's back to hoping you find this obscure item again... or just pick a different spell in the first place that just works all the time.
So, since I know some of my players have similar views on being put off certain spells because of certain material restrictions, I was planning on simply doing away with that rule in an upcoming game I'll be DMing (i.e. houseruling that all material components can be substituted out for your focus, including those with a cost, even if it says they are consumed, which obviously won't consume the focus if a focus is used; alternatively, Component Pouches just always happen to have those items in them, like the mere desire to cast that spell forces those items to spawn into existence inside the pouch).
My question is: What impact on gameplay balance would this have? I mean, obviously PCs (and NPCs) would have easier access to more powerful spells that otherwise have a sort of "cap" on them, so I might have to adjust the difficulty of encounters and such, but otherwise would it be so bad to effectively re-include the spells into the game that would otherwise exclude themselves by having unattractive material component restrictions?
PS: My home universe doesn't have resurrection spells, so concern about everyone just getting up all the time like everyone's a Zealot Barbarian all of a sudden is not all that relevant to this question; I mean, you can include it in your answer if you like, but I'd rather you not make it your main point.