I believe the currency conversion charge can be avoided by only charging your customers in your own currency or another currency you have a bank account for.It can, but then your customers get hit with varying exchange rates and potentially high conversion fees on their side. This will not make you popular with your international customers, at least the ones who didn't already back out when they saw a foreign currency anyway. Depending on which research you read, the rate of lost conversions due to lack of local pricing could be as high as 50%.
Within the overall landscape of payment processing options, Stripe looks trapped in an awkward middle ground now.
Above them are the merchants of record. Including currency conversion, international sales using Paddle seem to cost 7% + 35p at current USD/GBP exchange rate and their standard published pricing. But for that, you get real tax compliance.
Then we have Stripe, coming in at 5.9% + 20p (4.4% + 20p for European cards). Even with Stripe Tax, you're missing much of the essential functionality for global tax compliance and the reassuring liability shift, so that extra 1.1% + 15p or even 2.6% + 15p would be the easiest sale since bottled water in a desert to a lot of merchants.
Further down the price spectrum, we have services like GoCardless that are offering direct payment schemes rather than cards (duh) but for a fee of only 2% + 20p including currency conversion. You don't get any built-in tax support here, so it would be fairest to compare with Stripe at 5.4% + 20p or possibly 3.9% + 20p, but that's still quite a difference. And while you have to do your own tax compliance as with all payment processors using this model, you do get other benefits, notably in much improved reliability of collecting payments via direct payment schemes compared to card payments.
I wonder whether Stripe's medium-term goal might be to establish its own merchant of record service, and Stripe Tax in its current form is just the opening move. Otherwise, it doesn't really make sense to me as a strategy. But I have no inside knowledge on this and there are several Stripe people around who probably do, so no doubt if they want to elaborate at this time they will.