It's completely and totally worth it for smaller support squads for taking razorbacks for fire support as they do become really cheap relative to the perceived point cost of the jump packs at that point, however the problem with drop pods is the same thing that all drop pods suffer, in order to maintain a healthy squad after landing, it has to be a pretty full squad because it's going to be receiving a lot of fire before it's able to assault, which is the main objective of the assault squad.
The other problem is, yes you're able to get it basically where you want it, but after it lands, the mobility of the squad turns to crap. Least with a rhino it has the possibility of being mobile after the squad deploys from it and offers protection up till the point where they do deploy from it.
The third problem, and probably the main issue, is the vulnerability of the squad after it deploys. It drops in, gets where you want, but must endure a full round of fire. With Drop Pod Assault, you don't even have the option to really weaken the squads that might be firing upon half your drop pods before they deploy, which leads into a fourth problem...
...and that's the unreliability of reserves coming in after the first turn for pods. If you have multiple pods, half of them are going to be in normal reserves, which means it's random when they come in. Having your assault squads coming in piece mail is not a good thing as it leaves more vulnerability to the squads.