Is rail always the answer? No.
Should it be the answer more than it currently is? Yes.
For instance the Southern Approach to Heathrow, even ignoring the Waterloo services, could serve ~10 stations with >30 million existing passengers, which would provide local services when things inwards of Weybridge go wrong. Which if the services were also paired so as to run through to Paddington would help with travel into London at such times too. It would also mean that passengers could change at Woking and get a train to Old Oak Common for services on HS2.
With that number of existing passengers you wouldn't need much of a uplift in passenger numbers to see a lot of people using the services. Especially as there's existing services in the off peak which are 4 coach trains which are full with some standing.
Add to that there's also some significant developments planned for some places, including Basingstoke where is likely to gain another 50,000 in the next 25 years (IIRC).
Also bearing in mind that SWR is a net contributor to the existing network, having more trains running on the tracks which are otherwise mostly underused (basically on the Basingstoke/Guildford services once the trains reach the existing lines there's really only a need for works at Woking, Basingstoke and Guildford, all of which would be a nice to have regardless of if there were any new services and would be needed for Crossrail 2 as well, as they would aid in recovery when things go wrong).
It could even, if the Basingstoke service stopped at all stations West of Woking, allow there to be more services to Aldershot and maybe even Farnham. This could either be at the expense of 1 of the 2tph which are the Basingstoke Stoppers by diverting it totally or by splitting it at Woking, although at peak times the service patterns would likely be the same.
Although the above example could be a red rag to those who think that their region is also deserving of investment and why does London and the South East get all the money, it should be noted that I'm saying that there should be more money for rail investment and that I've just used a case which is local to me and I'm sure that there's examples of schemes which should happen all over the place.