Why 180g 45RPM LP's?... its true that you have to get off the couch to flip the records 2x more often than with a 33 1/3 LP and to really dial in the sound on 180-200g records most folks will have to adjust the VTA. Including the extra time for flipping, dusting, antistatic control and whatever else your vinyl ritual requires, playing a 45RPM can become quite the annoyance... until you start listening.
My first experience with a nice 45RPM album was joyous and bordered on the sublime. It was Horace Parlan's 'Speaking My Piece', one of the first Music Matters issues and the sound coming from the TT, I had never heard before - clean, detailed, well-paced and musical beyond anything that had been played on that TT - even the other standard weight 45PRM records in the stacks. I readjusted the arm to better suit 180g LPs and it sounded even better! Since then, I've been actively collecting 45RPM albums - I have a subscription to MM and I pick and choose the offerings from AA and others and I'm all the happier (and poorer) for it.
Now I'm not suggesting that everyone with a TT run out and buy up their favorite titles on 45RPM - it is expensive and there's definitely a PITA factor to it but if you have a nice TT setup, you really owe it to yourself to give it a listen at least once.
Back to the question...Why 180g 45RPM LPs? Well, why flip n' clean records when you can just insert a CD and press play?...Why not just download MP3 files directly to your network player and never leave the couch?...Why replace that perfectly functional zip cord with expensive speaker cables?...why upgrade caps, wires and tubes when the ones from the factory sound...'fine'?
It is all about the music and you can enjoy music coming from an AM radio and ear buds but most folks here want more - they want to get as close as possible to it and are willing to spend a lot of time, effort and money to get there. For me, 45RPM LPs just gets me a couple of steps closer.