I mean, yeah I would like to listen to Naruto's speeches and his 5000 flashbacks with that swing in front of the Academy, but does the villain want to listen also? They wait for the characters to stop talking or planning or whatever to attack. I don't really get it from the villain's viewpoint because it's better to just get on with it, right?
Anime comes from manga. And manga (and comics) as a story-telling medium is limited to panels. Each panel can contain a drawing accompanied by texts. The drawing can only show a "slice" of an event in time, since showing the entire sequence isn't feasible. For example, a hero running while talking can be depicted in a single panel with a lengthy dialog.
Since anime, like Naruto, are adaptation of the manga, these scenes are translated into animation with little divergence from the original material. And these types of scenes, where the enemy would wait for you to stop talking, flashbacks, or finished transforming, becomes more obvious and may look ridiculous.