Quality is not always the features in specs, its the way a weapon is utilised in combat and produces results. Quantity is important in a few ways, especially when there are enough guns to support all troops, which Pakistan has in good numbers to cover both infantry and armor, while India clearly lacks in armored warfare. Pakistan has good numbers of SPGs to cover all armored formations be it division or brigade level. Pakistan infantry formations are lesser than Indian infantry formations, so supporting artillery guns will also be lesser in number.Like have you researched? I did with Wikipedia and we were lacking both in quality and quantity
Deployment terrains are different, at some places its difficult to place 155 mm towed guns, while at some places mortars do the job easily due to better elevation angles. Some targets require heavy calibre weapon to take out in one or two shots where 203 mm will be used. Some 122mm artillery guns are easily traversed 360 deg without re-deployment even. 105 mm deployed in and around siachen area are useful and their ammunition is lighter so logistics is easier. So different calibres have advantages and constraints.
Artillery guns are not always numbers, range of projectile etc but they are also about strategic deployment, elevation angles, logistics of both guns and ammunition etc. These factors are overlooked when artillery is discussed. Effective and accurate fire by 6 guns is also useful than having 18 guns constantly pounding the same area and expending 3 times more ammunition.