There are a few teams missing out. Russia and Italy are missing from UEFA, Chile from CONMEBOL and Nigeria from the CAF. Unfortunately world cup only have 32 slots and one or two of the best teams miss out during qualification every time. Anyway, the chances will be lower for 2026 edition, as the number of participants is going up from 32 to 48. But the increase is mostly coming from AFC and CAF, so we may still witness a few of the good teams from Europe and South America failing to qualify for the main tournament.
I think it's better when a couple of strong teams miss the tournament due to the high level of competition than when the tournament turns into a huge number of meaningless games (due to a large difference in the teams' classes) and interesting games can only be expected in the 1/4 finals. Even in the current tournament, the group stage will not be very interesting, and in the next one everything will be much worse.
Again, I need to disagree with you. We are already having meaningless games. Even top ranked teams from AFC and CAF are unable to compete against teams from CONMEBOL and UEFA. I will give you one example. Remember the Russia vs Saudi Arabia match during last world cup? (inaugural match). Russia destroyed Saudi Arabia with a 5-0 margin. Now Russia is not a top ranking team from the UEFA. And yet the match was completely one sided, despite the fact that Saudi Arabia is one of the strongest AFC teams.