Very interesting question as are the answers!
As in any form of horse sport be it English or western, there are many rights and wrongs.
There are people who do only ride a dressage horse in an arena and many others who take their horses out for a good ride in the countryside and, at least in the UK, give them a good gallop and turn out.
Lower level dressage can be boring for the onlooker, advanced, especially a freestyle to music, is far more interesting.
Unless a person is interested in a particular form of equestrian sport, it can be boring!
Personally I like to watch showing classes in the UK. Watching parallel classes in the US is more boring than watching paint dry! To me Western Pleasure and English Pleasure classes are so unnatural that the only reason I can see for a horse moving so slowly is if it were going to its death.
The US Hunter/Jumper are boring, I doubt if any horse or many riders have ever seen a pack of hounds, and if they did then it would resemble nothing like they are piddling about at in the ring.
It is subjective. A Reiner should be able to appreciate Dressage, the two run parallel. Anyone who rides can and should be interested in other forms of equestrian sports. I enjoy watching Team Penning and Reining, I can appreciate the skill required yet my interests are purely English.