Just settle one make if you plan to go cordless. Multiple makes = multiple chargers and batteries
I agree with you. Multiple tools equals multiple chargers and multiple batteries.
I recently spent about £300 for a Metabo cordless drill. I was impressed that they are part on the One Battery Alliance (meaning that I could use the same battery in other tools). @JobAndKnock pointed out that the likes of Dewalt or Makita don't need to do that because they will sell battery versions of most of the cordless tools that you might need.
In my case, no one had a product that matched the desired specs- I was looking for a cordless drill that had a RPM of in excess 2000rpm- mine is 3000rpm.
Had Makita, for example, sold the drill I wanted, I would have considered buying makita tools. It is a lock in.