In projects/packages with a high volume of bugs, it's impracticable to follow up every comment through a mailing list, so people usually assign the user they want input to the bug. That's pretty much abusing the tool, because:
- as it may imply that the "pinged" user is the one responsible for the discussion to continue, but that's not necessarily true, neither most of the cases; Also more than one person's input might be required.
- there are a lot of workarounds to filter bugs in launchpad, it would be good if we could tell bugs are being taken care of by checking if they're assigned to someone (like launchpad team does).
- we could change bug's description with something parseable, but that would be yet another addition to the description which will become unmanageable soon.
- <add your own reason here>
A button with "Request user's input" that shows a person picker and send him an email requesting input might work fine.