Akuperma: You might be right about the positive effects of learning Hebrew or Yiddish, if frum schools would teach them in a meaningful way – as an example, the fellow who taught in Philly and published frumspeak did a wonderful job. But Philly is unique. Other yeshivas just learn Gemara in yeshivish and expect people to pick up the Yiddish or Hebrew.
Also, there is more to learning how to think than languages. Jewish schools don’t teach math, science, or history at all, nor can you propose teaching those in a meaningful way from a specifically “Jewish” perspective the way you could with Yiddish and Hebrew.
And it’s a huge oversimplification to blame immorality on secular knowledge; especially since almost all the things that I assume you’d point to as immoral are far, far less prevalent in the upper, more educated classes.
The fact is that a failure to teach secular studies works well for the 5-10 percent of the students who are going to become rabbonim and rebbeim, but at the expense of a tremendous handicap to all the others who won’t.
Jews were always admired for their intellect and for their respect for education, which resulted in tremendous accomplishment. Now, many brilliant ex-yeshiva guys are struggling at borderline manual labor because they can’t operate a computer. The level of discourse in the frum arena suffers because people know nothing about statistics or about government or about science. Even successful people are relegated to doing “gray market” type things to make ends meet and to function in the general world.