"You say that reducing the effectiveness of summon is a drawback. To who?"

To all of the summoning classes, for starters. One of the main strengths of the Paladin, Shaman, AP, and Necro is the ability to summon. Shaman have it earliest, but require empowerent. AP's and Necros get it considerably later, and must work harder to reach the point where 'summon' is effective and practical for them. It is not an ability that is attained easily from a design standpoint.

If the effectiveness of 'summon' is eroded, the appeal of these classes is likewise reduced. This change would also impact the conjurer class. They will be less feared in groups, and conjurers will be less potent.

"Summon is a useful tool, but also is a tool that can generate risk free kills by gank. By all means kill by gank, but accept, as a summoner, that you will incur an element of risk to yourself if you do. The change I suggest would mean that instead of death by gank you have an increased chance of those attempting to gank finding themselves having to fend for themselves, or that two groups fight each other in a more even fight. ... Would it have been more fun in that situation if the use of summon had actually backfire and sent the summoners the other way because of the mismatch in numbers?"

I agree 100% that less ganking equals more fun. However, I think your initial solution will immediately affect balance for summoning classes and conjurers. I *might* settle for increased failure rate in groups of 3 or more - but only slightly. You'd have to convince me that the benefits of this added restriction outweigh the gameplay costs. Remember, there are already existing drawbacks to summon:

Some Drawbacks of 'Summon':
Failure Chance
Delay (lag)
High mana cost
Requires empowerment OR significant investment of time to attain
Can be negated by Conjurers
Can be negated by other preventative measures taken by the target(avoidance/combat/saves/etc)
Does not work in nosummon areas, of which there are many

"Why is it every time someone suggests a change everyone assumes it is complaining?"

I don't think you're complaining and I think you have interesting points. Any change will impact someone who plays the game, so virtually every idea will face some kind of resistance or scrutiny before undergoing more serious consideration.