Why would Pakistan need anything with larger range than Shaheen-II? Our focus has been the threat from India and we have got it covered now. Longer range weapons will start to bring other nations within their range and a diplomatic unease will develop. Why make someone feel threatened when we don't intend to?
Our focus should be and has been on improving the accuracy and survivability of these missiles. Pakistani missiles are technologically advanced and this fact is acknowledged in serious circles. Raa'd comes in the same light, a technologically advanced weapon which can penetrate sophisticated defenses and get the job done.
Developing a cruise missile is no small job and making one which can be Air Launched is even more complicated. Very very few nations have achieved it on their own including India. Please keep in mind that missile technology is absolutely restricted and totally denied to Pakistan. China was nowhere in cruise missile scene at the time we were working on it. We must appreciate scientists and engineers at AWC who made it possible.
Comparing cruise missile to a ballistic missile is foolish. They are entirely different leagues. Apart from size, propulsion system and range, it is ultimately the purpose for which they are built. The CEP (Circular Error Probability) is determining factor here. Cruise missiles have very small CEP giving them capability to engage very small targets with great accuracy. Add the cruise missiles ability to evade defenced and everything starts to make sense. 350 km range? Make it 250 I say. If Pakistan takes out critical targets within 250 km of our border, India no longer remains in threatening posture. For deeper targets we have other missiles, to cover entire India. India has taken offensive posturing in the past. Cruise missiles are a good response to that. A very advanced weapon. But only those who know how this stuff works can appreciate. For others, Agni wins, congrats!