TBH, as much as I love the frequency of nukes on the field as it is, I believe it would be much more fun/fair & tactical if it was related to over-damage to the CT, thus a 'mech with no side torso left and only 100points of CT armour left (a few pixels long red bar) hit by a AC20 or Gauss slug would be something like 80% certain to nuke, hit by UAC20 or 2 Gauss slugs it would be 100%.
The same scenario for a BA PoV would only really be a risk of nukes if the BA fired a MP-PPC, but the threat would be lower than with 'mech weapons, with a burst of BA SRM, BA Small Laser or BA AC2 having almost no chance to nuke the kill.
Perhaps it'd mean a lot more nukes while everyone adjusted to the new overkill nuke mechanism (the 6 FB Shiva would be a nuke making machine), but perhaps it'd add another level of tactics ie. delivering the killing stroke with mguns and medium lasers because your 30m away; or, deliberately trying to make an opponent nuke to injure his lancemates who are too tightly grouped etc.
