Unlike, say New York, which was built from scratch relatively recently, London is centuries old, and as a result has grown in a pretty haphazard fashion. Unless someone is advocating razing the entire city and rebuilding from scratch, I am at a loss to think how travelling around it could be made any better.
As far as public transport is concerned there are buses as well as the Tube, and certainly the Tube can get really crowded, but the same is true of other major cities using similar systems; in Tokyo people are employed to cram commuters into carriages.
I work on the principle of not using a train if it's really crowded, instead waiting for another with fewer people on board, which usually takes perhaps one, possibly two trains, or around fifteen minutes.
I'm not sure about using the Tube every day to commute, but if I had to, I'd adjust my travel time to allow for the busiest periods.
S'not difficult, plenty of trains are running. Unlike public transport outside the city, where you might be lucky to get two buses a day. Each way.
And I really enjoyed spending two days on my own in London last August, travelled up on a coach, booked a hotel near the north side of Hyde Park, tubed up to Hygate and visited the Cemetary, then walked down to the Roundhouse for a David Byrne and St Vincent gig. The following day I walked across Hyde Park, visiting the Diana Memorial, the Serpentine Gallery, then tubed over to Southwark, had a look around Borough Market, had a pint, then walked over to The Shard, spent an hour admiring the view, then back to the pub for another pint, then back to Victoria to catch the coach home.
Absolutely perfect weather, and a really wonderful couple of days I'll never forget.
Several hundred photos prevent that...