Again wrong notion about warfare here.
Cost of a general Arty shell is around 1 Lakh/unit.
Even if we increase it 10 folds with RAMJET, it would cost around 10Lakh/unit. Now don't compare it with a guided shell at the drop of a hat. A guided shell like Excalibur would cost 2 times more because of its kit.
Now cost of a Pinaka Mk2 is 23 Lakh/unit i.e, double of a RAMJET powered shell. For each Pinaka rocket fired for 60 km range, you could fire two RAMJET shells. This is cost aspect of the shell over conventional shell and tube artillery.
Now a conventional 155mm artillery shell would weight 30 to 50 kg against a 100kg warhead of Pinaka. Now in our case, we can't go directly for caliber increment in case of a CFV. So when you have to target anything beyond the reach of conventional artillery shell, you have to go for Pinaka. This is going to cause collateral damage which would mean a global political issue. On top of that you would be giving an excuse to Pakis to use A-100 on you which could target you at 100Km. That means you would be keeping on escalating the game which you could have nipped at the bud with a cheap alternative.
So whatever you think of firing a shell or a war, Cost and Political implications are two important factors. So 155 mmm RAMJET shell is a cost effective solution which could bridge the gap between artlley and tube artillery. Just like Excalibur, which cost a whooping 44Lakh/Unit, it would be a special purpose ammo on our arsenal.