Complete SNMP support would be great, but there are some additional complications with sophisticated systems like MT. The thought of trying to control things like the hotspot, queues, policy routing, or the routing filter via SNMP gives me shivers.
As for exectuing a script from a file, you can just /import it, although last I tried there was some problem with a scheduled import, can't remember just what though.
I actually use a little python based system for bulk control, it maintains a dictionary of objects, each of which controls a MT via SSH. I can then just pass a command as a lambda to a subset of those objects, and it executes on each of them. I'm not using it extensively, mostly just a search engine for MACs, IPs, and usernames. I am also using it to keep certain firewall chains synchronised, but once routing-test becomes stable, I will probably replace that with a BGP based firewall control plane (it will be faster, cleaner, and won't require modifying the config for every change).
While my python based system works fine, it's hard on the poor little box running it, due both to all the code that needs to be interpreted, and the hundreds of SSH connections it maintains. A nice socket-based, or "C-shim-code" based API _could_ be alot more efficient. Some of what I do with this code could be easily re-done to use SNMP, but some of it would be quite difficult.