Too much of behavioral economics is motivated by a naturalistic rejection of "old" neoclassical economics without really understanding why the neoclassical assumptions are made, or when they are useful. Take the example of self-interest, which is really a tautological construction designed to highlight the fact that individuals have their own preferences which can be quite separate from social preferences (in contrast to the traditional social scientific view that people, in particular political actors, will naively follow what the "social planner" expects), and that these distinct incentives will have huge consequences for the applicability of some public policies. Of course, that rational choice paradigm has been turned into this huge strawman that all individuals are just giant calculators trying to maximize their pecuniary payoffs and hedonic satisfaction. Which is, of course, nonsense.
Believe me, the founders of neoclassical economics were not fools; they had to fight tooth and claw to get the rest of the discipline (then dominated by Keynesian style handwaving about human nature, which quite closely resembles some parts of modern behavioral economics) to follow their approach. And the rest of the discipline eventually were persuaded. The neoclassicists included people like Friedman, Buchanan and Lucas, who were all socialists in their youth. Lucas was actually a Marxist all the way until graduate school. Surely they didn't just become leading neoclassicists because they were naive. Even radical Marxian economists like Bowles and Gintis were later convinced of the usefulness of neoclassical economics (they are now working on evolutionary game theory), after Stiglitz managed to incorporate asymmetric information into the neoclassical framework. How easy it is to forget the knowledge that we've gained.
This is not to say that behavioral economics is not useful or that there aren't a lot of extremely capable behavioral economists; I'm only ranting about a small subset of the field. But this subset of the field is enough to make all of it quite meaningless; they produce strawmen to knock down; then others trying to point out that they are really strawmen, and in the end we've learned nothing. Or, in other cases, people find something that doesn't hold true in controlled experimental settings where the costs involved are insignificant; but some other people find out that it's a completely different story when you move to actual situations in the market. The work on risk aversion and prospect theory is the one field where I really think they added some value to "traditional" economics; but even then the significance is hugely overblown. I think there's a huge adverse selection effect here that dilutes or negates much of the productive ideas in behavioral economics and make people turn to polemical, poorly done research. (The fact that many of the more polemical behavioral economists gain tons of popularity from some political ideologues hellbent on proving neoclassical economics is evil is quite convenient.)