I'm not that sold on the Lumo model and even then, I think the ECML has the right mix of factors to just about make it work.
The problem is that slower trains are more expensive to run than faster ones. You essentially have your rolling stock and crew covering less daily distance, increasing the cost. Now, on lines with low speed limits and slower trains, this is probably a wash, because there are less strict maintenance requirements to poddle about at 40, versus say 140mph.
But if you are running an intercity service, you are certainly not saving money taking a long, circuitous route.
The most cost effective solution is to make the faster trains longer and increase their speed, so the same rolling stock + crew can complete more journeys in a day. Preferably on dedicated infrastructure designed with the stresses of high speed operations in mind.
It may seem ridiculous to maintain that going faster is cheaper, but just look at the cost of flying versus passenger ships for many routes. Of course ships even further show the cost of going slow, in that passengers require better accomodations for those longer periods of time (e.g. proper beds, sit down meals, activities, etc.) This also has a knock on effect on emissions - on transatlantic routes, the ships emit more carbon per passenger than flying.