Whenever I buy a new bike, it'll almost certainly have discs. No rim wear ever, consistent stopping in all conditions, wheel changes no more complicated- if not simpler- than with callipers. Bigger tyre clearances.
As for the OP: I have zero issues with the bike selections C+ made or the eventual winner. Lots of people, including plenty of people on here, can, would and do spend that kind of money on a new bike. It would be in my spending bracket for one. They made it quite clear that there were no bad bikes there, every single one was at least very good if not excellent for both performance and VFM. £2500 too much? Well, the £1500 ones were all pretty good too. The Viner Mitus for one. £1599 with full Chorus group? The Cervelo R2, a Paris-Roubaix winning frame with 105 for £2k. The Focus Izalco Ergoride, full Ultegra, £1700....The BMC was not the most expensive bike there, but it did have exactly the same frame as their top-level version (which would be racing if the UCI allowed discs). The same issue of C+ also had a test of £1000 bikes and a test of £300 bikes. They cover folders, hybrids, Moultons, the occasional feature on recumbents…The BOTY doesn't feature them because trying to compare a Brompton with a Trek Domane with a flat-bar Ridgeback (say) would be ridiculous. You don't use a sledgehammer when you want a screwdriver.....It would be equally unfair to compare a Trek Emonda SLR10 (£11k) with a bike 1/10th of the price. £1500-2500 is a reasonable spread of price and most buyers would find something suitable there, or have an idea what to expect from a higher or lower model from the same ranges.