It's the perfect way to introduce newcomers to the series.
This thread for MGSV.
The community thread for the older MGS games.
I think the Legacy Collection is the perfect way to introduce newcomers to the series. What MGSV is doing is like if Tolkien suddenly introduced an amnesiac Frodo in Return of the King in order to explain newcomers what's been happening in the last books.
Is it a way to welcome newcomers? Yes. But as a veteran Metal Gear fan I find the amnesia plot device as annoying and cheap. I already know what happened to Big Boss, the less I want is the game reminding me of all the events and people I already met.
But to each it's own.