They have 2 MegSafe versions in 10 years (MegSafe was introduced in 2006), the 2nd one was necessary to make slimmer laptops. Same thing with 30-pin connector and lightning. Lightning was before USB-C and it's superior to the old 30-pin connector.
Btw, MegSafe is one of the best thing about MacBooks, I'm actually sad they're not using it in the new MacBook.