The Su 34 has exactly the same role as the Jaguar . The Rafale was supposed to be successor to the Jaguar in the strike role . The Jaguars in the airforce right now cannot cover both CAS and strike missions (as they are too few). The Su 34 is a very viable option . Or go ask/beg the russians to make a strike version of the MKI . A F 15 E type upgrade . But the Russians don't care they like the tandem seat configuration of the SU 24 /SU32/SU34.Su-30MKI is a multirole fighter. Not a dedicated A2A fighter. A2A is its core competency though.
India doesn't need a light bomber like Su-34.
On a side note the airframe does not make everything . The Russians themselves are waiting for the Al41 to use on the final version of the SU34 (thats why it is in limited production now). Compared to Rafale the airforce may end up paying a lot more in maintenance due to the low TBO of the AL31s . The other side is the spectra that comes with the Rafale .. According to the internet it the best thing to happen to ECM since Harry Potters invisibility cloak.