I agree it's a dumb design. Relays do go bad and if you use resin, you have a mess to deal with trying to get them out. A real PITA. Relays, especially high-amp relays are pretty robust and can withstand some water and more importantly vibrations. Although high-amp relays usually have screws on the terminals and not just blades.
Also a bit silly to use solder-less connectors. Should be using a plug connector.
I really like my setup though. Simple and easy to setup and bypass/fix if needed. Although if I was going to do anything differently I'd change the 40A relay with a 75A relay but I haven't had any problem once I up'ed the wiring and replaced the ATC fuse with a circuit breaker.