Moderate abstinence (prishus) is a sine qua non for a life of avodas Hashem, and kirvas Elokim. Practically as a way of life, this fundamental truth can be very challenging; philosophically, as a matter of study, it is easily understood. Hakadosh Baruch Hu is purely spiritual. Accordingly, a materialistic person who pursues physical pleasure or wealth etc. distances himself from Hakadosh Baruch Hu and is ill prepared for the spiritual existence of olam haboh.
The indispensability of moderate abstinence underlies and informs parshas nedarim. The Torah severely criticizes one who is noder or nishba, "lo dayecha ma she'asra Torah - the Torah's prohibitions do not suffice for you!?" It is an act of hubris, bordering on the heretical, to override the Torah's divinely calibrated balance with nedraim u'shavuos. By way of example, if wine ought to have been categorically prohibited, the Torah would have done so. One can not be "frumer" than the Torah in this, or any other, respect.
This critique holds true when the neder or shavua is prompted by a misplaced sense of idealism. When, however, they are undertaken as a corrective measure, a neder or shavua represents a bona fide way of serving Hashem. Following up on our previous example, if one has previously abused alcohol and looks to a neder as a necessary safeguard, he is serving Hashem in accepting such a neder. He seeks not to override, but rather uphold the Torah's system of moderate abstinence. The Torah allows for a neder to address his individual, exceptional susceptibility.
The parsha of nedraim thus highlights the vital need for moderate abstinence. Everything the Torah's balanced system permits is intended for moderate consumption, on a per need basis. As necessary, one is allowed to accept vows/oaths to restore that balance which is so critical for avodas Hashem.