There is a misconception among some individuals that secular studies are in conflict with their faith. This may be due to their misinterpretation of the text "and you shall study the Torah day and night." To some, this implies that Torah should be studied day and night to the exclusion of all other studies.
However, the Jewish tradition also mandates that "every father must teach his son a trade," and nearly all of the great Rabbis of the past were well educated in secular subjects.
Another reason Yeshivas are reticent to provide a secular education is their fear of secular influences. But "secular" here is a misnomer. In fact, to properly understand certain concepts in the Talmud, an advanced knowledge of certain "secular subjects" such as mathematics is necessary -- and yet many ultra-Orthodox and Hasidic Yeshivas do not teach any math beyond basic arithmetic. Clearly, proper study of the Torah and Talmud practically demand what is today dubbed "secular education."