Furthermore, it seems unlikely you need all the software they are giving you. Assuming you are a software developer, you should be able to make do with open source alternatives.
i am a developer but i still need to do some gfx work for product flows etc
as a small angel round funded company not making any money there just isn't the budget, is my guess.
I guess if you have some in-house artists using Photoshop they should have a copy, I guess. But they could probably get by with Paint.NET[1] on Windows. petercooper mentioned two good mac image editing programs. Inkscape[2] is very capable for vector graphics. Sure Paint.NET and Inkscape aren't as good as photoshop, but people are using them to make amazing art so.
coffeenut/Locke1689 mentioned BizSpark, which includes MS expression studio. Really if you're working in a start up using Windows that isn't using BizSpark that's more than just a little odd.
I find it a little hard to believe that Keynote and/or Powerpoint are necessary. OO.o Impress[3] works just fine for everything I've ever thrown at it, including shoehorning it into making posters. Even google docs presentations are generally sufficient. But I also don't use the typewriter animation with the sound effect.
You mentioned Office, to which I would have two questions. The first being "Why?" And the second being "Why is OO.o inadequate?" I mean, are you writing .docx files, converting them to .doc, printing them to pdf, zipping them and then mailing them about for documentation? And even if you are, OpenOffice would probably work fine. It works especially well when you set the default to save as .doc/.docx (etc).
Finally, if it makes you uncomfortable I think you have to bring it up. Not because it's evil or incompetent or anything, but because it clearly bothers you. If it bothers you, your work output will decrease, you'll hate working, start eating bacon mushroom bacon cheddar bacon burgers for lunch and dinner to make yourself feel better and then have a massive myocardial infarction. All because of a little software piracy.
[1] http://www.getpaint.net/ [2] http://inkscape.org/ [3] http://www.openoffice.org/product/impress.html
Personally I disagree with your point on the GIMP. I've used the GIMP for years and find that just as good as Photoshop - but then again I've used the GIMP for years, and more than photoshop.