They have the motive and this is just as plausible as the absurd high tech idea being floated. Both Israel and Iran benefit from increased tension before the new administration is in office...
Could the Iranian state be responsible for this? Possibly but not particularly likely, could it been an internal conflict within the IRGC or between the IRGC and the local criminal underground (yes this is a thing, the IRGC often supplements it’s income by running criminal enterprises in the region) a bit more likely but still less likely than a combined western effort to take him out.
I don’t think Israel could or well would pull this off alone, by all accounts whilst Israel does operate a very large humint network in Iran much larger than the US ever managed to set up (in fact by published accounts, Israel is the one who’ve always provided the human element in joint operations) they still heavily rely on US intelligence and operational support.
Before JCPOA was signed the “rumor” was that one of the sticks and or plan B was a pretty extensive plan to take out quite a few very high value Iranian targets of the map and that plan didn’t include buildings but rather was a direct threat to essentially take out anyone of any importance especially in the IRGC.
This seems to be the second and quite likely last at least for a while (due to the US elections result) operational use of that “backup plan”.
As far as conspiracies go or at least corruption I would put KSA pressuring Trump to do something before he leaves office in exchange for financial favors over anything else.
This is a more thorough and believable report: https://www.dailymail.co.uk/news/article-8997575/Assassinati...
(However, that site is a nightmare of ads, popups and auto-playing video, only legible with uMatrix.)
2) Daily Mail article is more thorough and believable than a tweet sourced to IRGC propaganda
Both statements can be true.
It's also legible, I'd even call it pleasant, with Firefox plus NoScript. Many sites block or degrade images when JS is disabled, but not the Daily Mail.
Because a public story completely unconnected with the facts give your adversaries no information about what you've actually worked about the attack.
Why would you use that particular story may be a harder question, but a robot attacker might have a better propaganda look than something revealing, say, betrayal by agents within highly-trusted security services.