Can we please get over this irrelevant red herring of obstruction lights. They have little if anything to do with this case. They are there to indicate the presence of an obstruction that can be seen. ie in VMC. They are NOT there to indicate anything in IMC for two very good reasons.
1) They cannot be seen in IMC. D'uh oh!
2) No one should be flying in IMC anywhere near them so there is no requirement for this to be a function.
It is abundantly clear that this accident was caused by flying in marginal VMC or in IMC whether intentionally or not, far too low and bumping into something that wasn't seen due to the met conditions. Simply put, the poor fellow got himself somewhere where he just shouldn't have been in such weather and got unlucky.
Changing rules and regulations on the basis of this accident would be unnecessary and counterproductive, it certainly wouldn't/couldn't prevent a future accident if the same sort. Only an individual pilots judgement/awareness is capable of doing that, and I think this unfortunate accident has done plenty to raise awareness of the inadvisability of grubbing around in poor vis below obstructions with their tops hidden in cloud instead of diverting somewhere more suitable.