Keg,
As a practical matter your thinking is reasonable however there are three key points to remember
1. You can only do this your way if there is no chance that the airport and that particular RW, having opened, will not close again. Space doesn't permit the recounting of a zillion examples where pilots got stung by this one. At Seoul/Incheon there is no real problem because we use Cat 3b, but a Cat 1 or even 2 operation can find the fog extremely unpredictable. It moves around with a mind of its own. The time from the hold to your approach might be 10 minutes and I would not want to bet the family farm that things wouldn't change.
2. Legally of course, if, despite from your seat, it being a CAVOK day, the airport still requires an alternate then despite seeing the RW from the pattern, you can't go there. (Mind you, in another life I used to be able to see the RW at Launceston often only to find that at the minima it had gone: memo to young pilots, don' trust your eyes). The question of how you know whether an alternate is required and how that requirement can be changed at short notice is an issue all of its own.
3. Keg, you're not a captain yet but by the time you've been in the LHS a few years you'll have had to do many things which at that time seemed mindlessly conservative. The safety of the whole operation rests on that though-better a hundred unneeded missed approaches than one that should have gone round but didn't. As a matter of airmanship I try to tell our pilots that last minute decisions by the PIC to continue because "things seem better now" (WX, a cargo fire warning, etc) are almost always wrong. In very recent history Qantas has seen the two extremes. QF 1 at Bangkok where the PIC suddenly belived the weather was OK and changed his mind.....and the 330 at KIX where the crew flawlessly did the right thing, not even wondering whether their cargo fire warning was "false"; Second guessing forecasts, warnings or even current conditions using the MK 1 Eyeball is a suckers game. Make solid plans early and stick to them. I don't mean to preach at you at all.... but the road to hell is paved with good intentions and thats not what the SLF pay for. They like grey hair and conservative decisions every time!
Long term fix for Sydney is of course for at least one RW (34L?) to be cerified for Cat 3b. As TAC ON suggests, for Australia's premier airport this is hardly a revolutionary concept. My airline pays a lot of money to maintain a flawless 3b capabiity and a lot of money to land at Sydney. To be unable to land because of reduced vis when 3b and a 100 ft Alert H could easily get you in is very third world.