I think that time to solo is not a significant indicator of eventual pilot ability. It has certainly increased since say 1950, not due to any real change in the aircraft but rather the training environment. Just look at the activity levels at for example, Wellesbourne compared with a large grass field with two or three aircraft clear of controlled airspace.
There are a number of exercises that the student must complete before a skills test, and should compete before solo. I don't think it is realistic to expect the student to be solo even in benign conditions unless they can safely and with some spare mental capacity fly all the manouvres needed for a circuit, be able to recognise and recover from a clean stall and the approach to a stall in the approach configuration (recovery at the stall warner with minimum height loss) cope with a simulated engine failure at any stage of the circuit and execute a go around on their own initiative in the case of a balked or bounced landing.
They should also be able to divert to a nearby airport if flying from a single runway airfield, be moderately competent on the radio unless flying in a non radio environment, and feel comfortable with the knowledge that they will be the captain, solely responsible for the safe conduct of the flight.
We have gone from a 35 hour to a 45 hour PPL and added layers of complexity to the task in the last 60 years. We expect a learner driver to pass a test before solo, not to drive around on their own less than half way through their training. What's the rush? We all have financial constraints, but the student pilot needs to learn to fly safely, not to enter a first to solo competition.
My personal opinion is that most pilots are in the circuit too soon. There's a high workload involved in flying a series of circuits that is not compatible with learning basic handling skills. There is no need to bash around learning straight and level in the local area, it can be done on short cross country flights, each one of which starts with a takeoff and finishes with a circuit and landing. This will inevitably involve all the activities required to solo, but in a less stressful situation. Then when the student is competent it is time to do some more concentrated flying before solo. Not two hours general handling then twenty hours going round in circles......
With the added benefit that they will know their semi local area and will be less likely to get lost close to home!