I know PHP has a weird history of rebelling against its C-family-syntax heritage, but requiring the syntax in your example would seem specifically calculated just to make developers' lives harder.
Your example would work, but there's a reason you might want different keys. My company's current web app is written in CakePHP, which has a love for arrays. Some of my queries look like this:
Personally, I'm quite happy with VPS and would never go back to shared hosting without a good reason. But if you're writing software that is going to be used on lots of "standard hosting" packages you have to take this kind of delay into account.
Sadly, it will be years before the majority of hosting providers adopt 5.4...