Actually the C27J is an Italian aircraft from Alenia, it just has similar US parts of the C130, for commonality reasons and lower costs.
You must keep in mind the situation of IAF, with all the old HS 748 and AN 32. MRTA, or RTA which should be in a comparable class of C27J, won't be ready anytime soon, so adding already operational and proven aircrafts is a good idea.
From what we know so far, the future IAF transport fleet could look like this:
Saras - very light transport
C27J / RTA 70 - light to medium transport
C130J / MRTA - medium transport
IL 76 / C17 - heavy transport
(A330 MRTT - which can carry 45t of cargo, while doing the tanker role, would be a great addition too)
Not a bad mix of specialised foreign aircrafts, in lower numbers, as well as new developed aircrafts with Indian content, in higher numbers.