In Erope destination only fuel is only permitted if the weather is VFR, and two independant runways with two independant approaches are available. In practice this is never used, and an alternate is carried on every flight - even CAVOK days.
I beg to differ. It can be, and is, regularly used, when practicable. Like any other procedure it has it's advantages and limitations, but it is indeed used from time to time.
TAF 010/15 BKN 1500 15/3 1013 TEMPO BKN 0100
(i.e. TEMPO below the landing minima)
In Europe you may disregard this tempo, and still only carry a single alternate - of course this carries the risk that the weather is actually present on arrival, requiring a divert. Any holding is at the pilot's experience/discretion.
Assuming you mean BKN015 TEMPO BKN001, that does indeed have to be considered as BKN001, at least where I work (which is in Europe).
In Australia, planning to this destination at all is probably not permitted under CAR 257.
What if you're going A to B, and B is forecast below operating mins. Can you then file a flightplan to C with alternate D, both being above alternate mins, start out on that flight, and then change your destination enroute (to B), if the weather at B clears up to permit approach?