Inevitably when this discussion begins someone chimes in to note the issues with AI. Yes there are some issues. Like when my healer hireling heal-kills my Kindred Being lich or skeleton knight. Sometimes summons become passive for no apparent reason. But even those issues are mitigated by changing the build around.
The main issue with summoning-focused builds is that they simply don't scale adequately. They are 99% dependent on feats and epic destiny choices. There are some class enhancements that are available (PM skeleton knight boosts, druid wolf boosts, warlock enlightened spirit) and some class-based abilities (pretty much just druid's "pack" line of spells afaik), but even if you combine the best of all of that, they are still pretty weak, and get wrecked on anything above Hard. The only gear-based boosts I know of are the augmented summoning topaz from feywild (but if you are going for a summoning build this would be useless, as you will need the real feat as a pre-req to get other stuff that's mandatory for the build) and the cry of battle filigree set, which while good, is not going to carry this build by itself.
To make summoning viable DDO needs one or more of the following, irrespective of AI changes:
1) Add at least one new item suffix to the random loot table and possible one or more new ones for named items that applies to summoned creatures, hirelings, pets as the augmented summoning feat does.
2) Make pets scale off modifier of the highest ability score of the summoner in some way. E.g. Increase the PRR/MRR/MP/SP/RP of summons by an amount equal to the modifier of the stat, or some percentage of that modifier. This allows pets to scale better as the key ability score increases.
3) Add additional pet-related feats. Move Improved summoning down into the higher heroic levels, and add a new Epic Improved Summoning feat in the epic levels.
4) Modify the reaper cores for one or more tree to passively buff summons per point in the tree. Currently pets are or questionable value in elite, even when buffed to the greatest extent possible, and worthless in reaper no matter the build.
5) Cause pets to scale off of maximum caster level (as boosted by enhancements or destinies) instead of only natural caster level, either directly or in some percentage.
6) Add another universal enhancement tree that focuses on a pet-centric build.
Personally I prefer the options that require me to give up something (a feat slot, an item suffix, a new enhancement tree) to specialize vs just scaling all pets up, but I think I'd be happy either way. As I said, obviously there are some AI things that could/should be addressed, but even if they were, the fact is that summons simply do not scale well enough to be impactful beyond Hard, which is a problem when a big portion (i would say majority) of the population plays exclusively Elite/Reaper quests.
Your thoughts?