Actually I'd say the principles of track circuit block and colour light signaling are far simpler than those of Absolute Block and semaphores. There are so many complexities and apparent oddities such as the principle of one distant applying to several stop signals (except when it doesn't) and all the extra controls added to the basic system in later years to protect against human errors.
So while TCB is less interesting it's also easier to learn. While textbooks such as the Kitchenside and Williams ones (again from distant memory on my part!) tend to go through several chapters on AB first, its rarity these days as well as its complexity means I'd probably recommend anyone wanting to learn about British signalling to ignore it until they fully understand TCB.
Thank you for the observations.
One of my spotting stations (talking long ago...) had a 'box at each end of the station, and I never did work out which was the home and which the starter for each box - or indeed, whether all signals were actually present: reality is often not as straightforward as the theory!
One of me friends drives for SE Trains and he's mentioned that newer drivers (whose understanding of semaphores and block signalling is possibly limited to knowing which ones you have to stop at) are un-nerved by the apparent randomness of the location of semaphores - you go for miles without seeing one, then there's a cluster.
You may also recollect the Grand Central driver who encountered home over distant, showing stop and caution respectively, at night. What he saw was, of course, red over yellow; applying logic he assumed that only meant some sort of caution so carried on at pretty much full speed - I think a LC may have been involved (there was an RAIB report).
So I can see how the observation you make, that TCB is easier to understand, is very true.