They write the thing the way they are written because likely there was a case where simpler language lead to the company losing in court. There's also a principle Contra Proferentem, that intreprets all ambiguities in favor of the non drafting party, so the drafting party should be extra careful and write all this pesky legalese.

There is no reason why terms should not be written in plain English and indeed under European consumer protection laws, you should be writing the terms in plain English because it means the user has a better chance of understanding them, and (regardless of the first part) you have a better chance of enforcing them should the need arise.

Please be aware that not all lawyers are the same and you can find many who will be more than happy to write a set of terms that are in plain English, ambiguity-free and protect your company against any areas of concern that are legitimate for you to protect against.