My conspiracy theory is that bigger firms are expected to have PR departments, and people working in PR departments are expected to write longer paragraphs to justify their existence.
Having worked in PR, there are no length requirements or even people valuing wordiness.
What does exist is a stifling press release style that everyone loves to write and no one loves to read. It doesn't mater how long each thing is, but you need "about this company" and "about that company." You need garbage quotes from the execs (written by the PR guy of course), and you need everyone's statement of business in the first paragraph.
So, with all that crap, you already have a page of nonsense. Then, add in a few paragraphs on the actual announcement, and that is how the sausage is made. Some press release writers are better than others, but no one can write good press release.
Personally, I don't write press releases anymore. I write casual blog posts.
