Yes, but then why not maximize profit even more and let all, US costumers included, download from the server in Ireland.
Because someone knowledgeable [ie, exactly NO ONE speculating/bitching here or elsewhere,] about Adobe's interests, considered as a whole, has determined that this procedure will not best serve the needs of the largest number of its customers in such a way that maximizes Adobe's profit. There's no ethical or moral reason they couldn't do just that, if in their view it would better serve customers--as they are able to determine this--and maximize their profits.
Understanding all this is really quite simple, folks, once you've discarded the socialist / collectivist notions that profits are evil; or that corporations exist merely to provide a pot of money to fund the aspirations of grabby governments or statist do-gooders.
Corporations are merely organizing structures. Their ONLY purpose is to harness the collective expertise of groups of people, and manage the flow of invested capital, towards the production of products or services customers want to buy, at a price that exceeds production cost by a large enough margin to ensure an acceptable return on invested capital.
Every other role heaped upon corporations by outsiders is little more than expropriation of private property, called by whatever name is in fashion at the moment.