Well, the monopoly aspect has had a limiting effect on a few things I've been involved in, at least in government/quasi-government. Given that some data series I've used are only (? or most conveniently) available through the terminal, it has meant having only half-automated tools. You always still need to do a weekly walk down the hall to a terminal followed by a lengthy boot-up on an old box, entering of password, opening of spreadsheet. They tend to lock down those machines too.
While I guess there are APIs, I don't get the impression they're easy to just integrate into any old workflow if the terminal is down the hall or even on the other side of your desk. It's all linked to that terminal, no? Pretty annoying if you ask me, from a programmers standpoint. Not to mention another case of closed, proprietary tech in the financial sector.
In many cases it is not Bloomberg's monopoly but the data provider's. The licensing and royalty agreements between Bloomberg and the data provider have very onerous terms including restricting how many screens the data can be displayed on, what mediums the data can be transferred to, and where and for what purpose the data can be used. The terminal restrictions and API limitations that Bloomberg imposes are usually driven by these concerns.
Bloomberg offers less restrictive APIs but they are even more costly than a terminal license and often require the end user to sign agreements with the data providers directly and pay additional royalties.
While I guess there are APIs, I don't get the impression they're easy to just integrate into any old workflow if the terminal is down the hall or even on the other side of your desk. It's all linked to that terminal, no? Pretty annoying if you ask me, from a programmers standpoint. Not to mention another case of closed, proprietary tech in the financial sector.