I don't agree that race/class restrictions fix that problem. If you have players only playing a small selection of the available races, that's a development issue and likely boils down to one of two things: either racial abilities aren't balanced, or some races are just better designed in aesthetic or animation than others. Trying to force players to choose a race they don't want to play just so they can play a specific class is not a good way to fix either issue.
As an example, FFXIV has no racial abilities or bonuses and every race can play every job. While a couple of the races are a little more popular, you still see every race represented across the community. By removing any min/max reasons to play a specific race, players are allowed to choose the race they like the look or concept of most, thus greatly evening out the statistics of races played.
If you have race/class restrictions but racial abilities aren't well balanced, people won't choose to play less popular races in order to access a class the more popular race can't play as; they'll just stick to the classes that can have the more powerful and popular racial traits. In WoW, a game that has a long history of race/class restrictions, certain races have dominated the landscape while others are barely represented specifically because some racial abilities are considered more powerful and more desirable than others, and the fact that there is a small selection of classes available to the more popular races doesn't force players to play other races. With race/class restrictions, you will always have one race considered to be the best choice for a class, and a large part of your player base will choose that "best" race/class combination just out of fear of missing out on a small percent of power.
That's another double-edged sword. I find Final Fantasy a very bad example. Final Fantasy comes from the Asian region, and there the gameplay is generally somewhat different from that of us West-Eastern Europeans and North Americans. One must not forget that the community was so dissatisfied with the game that the developers rebuilt it from scratch. I think it's justified that not every race can play a class. For example, lore-wise I would never give an Orc a wand. Orcs are strong fighters but not wand wielders :D The racial abilities don't matter much, that's really only a few percent that make up maybe 10% of the players from all over the world. The racial abilities can be neglected as a normal player, and you can play the race you like best. To get the most out of it, you play the class with the best racials. These are crucial in the high tier endgame, but only if you want to grind hard for a progression or become the first on the server.