Yes it would be nice to be able to have access to a few debuff settings that you might normally get from a group. The other option right now is to just grab a friend and have them do it.
However, if you apply breach or fracture yourself, you have to modify your rotation, resulting in a DPS parse that is at least somewhat artificial. What do you think?
All dps parses are superficial, I've never met one person yet who uses a self heal as they would in actual gameplay or refreshes shield every 6 seconds so applying your own debuff is really a small matter... That said though I agree that practice dummies should have settings that can be toggled to simulate breach/fracture
For most Magicka DPS, elemental drain is primarily used for the regen. A 13k resistance dummy would probably not provide minor Magicka steal, so ele drain would still be needed. If the extra 300 Magicka per second is not needed, then anyone is welcome to use the elemental susceptibility morph (which has infinite duration). For either morph, I like when Magicka DPS cast their own debuff, because it ensures that they have a bar slot available for a shield in trials.
Your idea would work better for stam sorc and stam templar, since neither has access to Major Fracture without using sword and shield. All other stam classes can have near 100% uptime on Fracture just by doing their DPS rotation.
Introducing more dummy types just adds more variables into parse comparisons. More questions will have to be asked for an apples to apples comparison (right now it's really just normal vs robust, and self-buffed vs group support). I don't think additional complexity justifies the convenience of 2/10 DPS builds no longer requiring someone to puncture their DPS parses. Just my opinion of course.
I would not suggest the target dummy needs to be debuffed automatically. The effect of it is something easy to calculate since it is known. Basically, not needed and really does not serve any purpose.
What would be good is something we could obtain for resource supply since in an organized group we will have resources provided. Without this we have to bring someone in to help or adjust our rotation which defeats the purpose to begin with.