I personally love having a hard currency, and certainly miss it. I suppose me and my players just like having a currency to tally and count. Just making rolls for everything is boring, and leads to a little less variety. And influence counting as bribes, favours and so on has always rankled me, since it implies that every new character is someone with wealth and sector spanning reputation. You've just rolled up a new feral world guardsman, and it just so happens that this influence roll mean that he is well connected on Forge World XXI, and can pick that new gun right up.
For my games, I plan on using both influence and currency. Macharian Handbook as a baseline for all prices, since it covers Heresy 1.0 and Rogue Trader, and since they are similar power levels, the prices carry over with no problem. And when it's prudent for a player to acquire an without currency (like actually having a contact on the world, or openly displaying their power) then Influence comes into play.
I am afraid this is one where I agree with you, but there are a lot of people who will disagree because they do not like keeping track of money. However the whole influence idea is really a bit daft. A noble from a small agri planet is probably going to have less influence compared with a minor Tech Priest from Mars. However in both cases the level of influence they will have on any other planets is probably about nil. It will be organisations in the 40K universe that will have influence, rarely individuals.