Allow me to quote a post which sums my opinion perfectly.
http://www.reddit.com/r/nintendo/comments/3aucfl/the_day_the_fire_emblem_community_collectively/
- "Optional" is not always optional. These features are not absolutely necessary to beat the game, but neither is 75% of the features in the game anyway. The "optional" features are supposed to be what makes the game fun, otherwise it is a very dull and featureless game. These "optional" features which have nothing to do with strategy add up to a substantial amount of content in a strategygame. When you don't enjoy the "optional" features, there is not much left to enjoy.
-These features are integrated with other features. You cannot forge (a long-standing FE feature) without mining (a feature that has nothing to do with strategy). You cannot buy weapons without building a castle. Your ability to build supports depends somewhat on your willingness to rub people. All these things force you to use features you don't want to use in order to use features you do want to use.
-These features cannot possibly be balanced. Either the game expects you to use them (and therefore is too hard if you don't) or it doesn't (and therefore too easy if you do). The first would obviously be worse than the second, but either way is completely unbalanced on one side or the other. So any feature that gives a tactical or statistical advantage is never "optional."
-The longer these features exist, the more likely they are to become integral in future games. Example: reclassing was introduced in FE11&12 and was (more or less) optional. It made the game easier, but the game is not substantially different with or without it. You could choose not to use it and be fine. In Awakening, they made reclassing an integral mechanic, beating the game without it is substantially harder, and you cannot take advantage of the skill system or do any of the postgame without it. A huge amount of content is locked behind that.