It's for the annual reports and 'best place to work' advertising. Big corporations want to show how diverse they are. It might hence improve your chances to get hired if you fit at least in one of the minority categories.
Long time ago I worked in a small company were they hired a deaf girl as a trainee. One might think that it's so nice that they give disabled persons a chance (in her case the inability to hear unfortunately affected her ability to read as well, to the point that my boss discouraged me from teaching her the use of e-mail) however the company received some 100 grand/a (a lot of doe in Germany then) from the government for her professional development, so the company gained a little even if she wasn't all that productive. I don't think the company had any intention to hire her afterwards.
Long time ago I worked in a small company were they hired a deaf girl as a trainee. One might think that it's so nice that they give disabled persons a chance (in her case the inability to hear unfortunately affected her ability to read as well, to the point that my boss discouraged me from teaching her the use of e-mail) however the company received some 100 grand/a (a lot of doe in Germany then) from the government for her professional development, so the company gained a little even if she wasn't all that productive. I don't think the company had any intention to hire her afterwards.