Disclaimer: I am not employed by WA nor am I privy to their internal discussions, the opinions expressed here are mine and mine alone.
From a business logic point of of view I can fully understand WA developing PS for the american market only at the moment as the potential market is huge. Plus there are other considerations to take into account like understanding the US market, support for shippers, payment gateways, local taxes etc.
In comparison to support the european market they have to add support for 2 currencies plus different shippers, payment gateways, VAT etc. This would mean a lot of extra work both in terms of development and support for the product.
Powerstore is an inexpensive solution at the end of the day and it is almost impossible to make something that suits everybody, if you cannot make the changes you need yourself ask on the forums for help from your peers or advertise in the Job Forum for someone to do it for you. WA have made their position on this clear so it's your choice at the end of the day.