Charging is great, but there are a few things that make it problematic to use in play:
* You can only target mechs that have already moved
* It counts hexes moved, not MP. That Spider might be charging 12 hexes in a straight line, but far more often will have to turn, change level, go through forests or similar, which dramatically reduce the actual movement. (If you *do* get charged for 12 hexes, then you probably deserve the pain).
* Charging is declared during movement, but is resolved during the Physical Attack step. If the Mech is blown up, or fails a Piloting check beforehand (typically for taking 20+ damage in a phase), the charge attack automatically misses.
* To successfully charge someone requires a Piloting roll which is modified for movement, terrain and the difference between the pilot skills. Your general pilot with a Pilot 5 skill would thus generally need about an 8 or higher to successfully charge (+2 Running, and say +1 for target movement). This is an acceptable chance, but not a great one. Charging becomes a lot better once you have very low Piloting skills. (Same situation, P2 vs P5 means you only need a 2 to hit!)
* Meanwhile, you're in point-blank range of their guns. Charging a Hunchback doesn't seem such a good idea when that Spider takes a AC/20 blast to... anywhere, really.
* Oh, and a Charging Mech can't fire weapons.
I've seen charging be really effective, but often the map is too cluttered for most mechs to easily do so - or with a good chance of success.
Jeff, are you using the current set of rules? There have been a few changes over the years - not that many, but they can be confusing. (The best change is the new Partial Cover rule, which means that standing behind a hill doesn't mean a 1 in 6 chance of the head being hit...)
Cheers!