Architecture was awful and depressing
The castles, which are considered the best examples of architecture from that era, belonged to the wealthy, important, and powerful people such as kings, nobles, and knights. However, castles were designed to protect their owners from rivals and invaders and so what mattered most wasn’t how “beautiful” they were but that they be impenetrable to attack. This is the main reason most remaining castles in England look so depressing and gray.