One issue is that some classes of users and locations (e.g. Trading floors) are restricted by law concerning the communications systems they can use for work because all communications regarding financial transactions has to be auditable.
On the other hand most of the banks have their own internal software libraries you can install stuff from and you get a bunch of useful utilities by default such as Irfanview, notepad++, Greenshot or similar. Machines for devs are often less locked down.