I am surprised that more people do not agree with you about these two abilities. Rook really got the short end of the stick on this one.
Compare level four abilities:
1.5 second cast
10 sec cool down
.3 second cast
7 sec cool down
1650 damage over ten seconds
Initially the statistics look like they match up well. But analyzing actual play gives a different story. We must take into consider that DGs will are very mobile and that lag exists in all games. What this means for hammer slam is that you cannot reliably strike with the ability unless you first hit a DG with Boulder Roll. Essentially this means that the true cooldown for hammer slam is 15 seconds. In the same period UB can launch two spits and an additional auto attack during the casting time of HS alone (this is true even for an ooze UB that simply uses spit for extra dps). In this scenerio the range of BR simply does not matter. The combo cannot be executed unless you are within melee range. With lag the timing of the combo can easily be thrown off. If it is then another 15 seconds must pass before HS can be used reliably. I think it is best to sum up the issue in the following lists comparing the conditions for using each ability (I will list HS and Spit in reverse order):
1. Melee range
2. 950 mana
1. Melee range (the slow speed of Rook makes this more difficult)
2. 840 mana
3. Target frozen.
4. No DG near with interrupt ability (this is the most eaily interrupted ability in the game).
5. No lag during period target DB is frozen.
The last three conditions for HS dramatically reduce its use in real play. A missed HS is worthless. You do NOT miss and you do NOT fail to do serious damage with Spit. Countering HS requires moving a couple squares on the map or interrupting a 1.5s cast. Counting spit requires selecting a particular demigod or selecting a specific favor item. Spit is clearly more powerful in actual play.