In terms of the system in general or specific members thereof, anonymous?
If we’re referring to the system in general, I for one can’t entirely complain. While it’s true that a region can get by without any form of organized league (take Alola until recently, for example), leagues—and thus, the Elite Four/champion by extension—often function to bridge the gap between that region and the rest of the world. By offering an organized league, foreign trainers are more likely to explore the region, and in return, they bring revenue and push regional governments to improve infrastructure (among other things), particularly to gym-hosting towns and cities. Moreover, for researchers, it means trainers help us discover new pokémon, which brings us even closer to understanding their world—and ours, for that matter.
Of course, there are downsides to a league presence in a region. An increase in foreign trainers means an increase in human traffic in untouched wilderness. With an increase in human traffic to such areas comes the spread of disease, the accidental introduction of invasive species, poaching, population disturbances, and quite a number of other risks and dangers. Granted, yes, that would be what the Pokémon Association is for, but rules and regulations are only as good as the people who follow them. That is to say, unless both regulations and enforcement of such are equally strict, the concern of human traffic to previously untouched wilderness is still a valid one, given that organizations such as Team Rocket still exist.
That and, of course, in some cases, a region lacks a league for cultural reasons. Alola was far from the only region to resist the implementation of a league for so long; in some countries, it’s even seen as akin to imperialism. (It certainly doesn’t help that the concept originated in Kanto, which has had … quite an unfortunate history, I must say.) In those cases, I believe that the people’s concerns are just as valid as any towards human traffic, and their wishes should be respected. It just so happens that in some cases, a compromise is capable of being reached—as in the case of Alola. But I do recognize that’s not the case for every region in existence.
If, however, you mean to ask how I feel about the Elite Four and champion separate from the league, it’s absolutely possible to have one but not the other. Take the Orange Islands, for example, which lacks an Elite Four but has a champion who also technically serves as a fifth gym leader. For smaller regions, it’s absolutely possible to be creative with the setup for your league, and the Association is often accommodating for those cases. However, larger regions often need a more significant payoff, so to speak. After all, larger regions ask trainers to go through eight full gyms before even thinking about a final battle for a title. Of course, in these cases, regions often give registered trainers a choice between a tournament (the more popular method, as more people can participate in them) and the Elite Four gauntlet (far more challenging … but also far more difficult to arrange), but either way, the option for either challenging fellow trainers in a grand tournament or the best trainers in a region is often a fantastic incentive to push trainers forward from their first badge to their last.
In short, anonymous, it certainly depends on what you mean by your question, but generally speaking, I’m rather for a league—and, by extent, an Elite Four and champion.