First off, we're looking more at Article 1, Section 7 of the NJ Constitution as opposed to the Fourth Amendment. The United States Supreme Court has stated that DUI/DWI checkpoints are constitutional.
Wikipedia and CaseBriefs give good summaries.
TL;DR - Fourth Amendment can be relaxed if there's a significant government interest. That government interest is "Curbing drunk driving." 3 Justices disagreed, and we still think of them highly. So your opinion is more than understandable, especially given that 3 SCOTUS justices agree with you. However, the Supreme Court is the end all be all unless they reverse prior decisions (rare) or a Constitutional Amendment is made (even more rare).
So now we go to New Jersey. State v. Kirk notes the following (stolen from Westlaw)
(1) State Constitution was more appropriate vehicle to resolve questions concerning rights of citizens to travel on highways of state without police interdiction and rights of police to use reasonable methods to enforce traffic laws than was Federal Constitution;
(2) temporary road block set up by exercise of absolute, unbridled discretion of officers in field, which involved no command or supervisory participation, for which there was no demonstration of need or efficacy at particular time and place, upon which there were no limits or directions of any kind as to how, when or where road block was to be set up, or as to why it was set up, and purpose of which seemed to be little more than to give officers something to do, was violative of State constitutional provision against unreasonable seizure; and
(3) if certain procedures set forth, ensuring supervisory control of check points and warning to motorist, are carefully followed, any constitutional objections will be overcome.
TL;DR - it can't be "Hey, let's set up a DUI checkpoint!" There has to be facts to support its need, let the public be aware of them, and to make sure there's approval for them.
This has been upheld many, many times since the initial decision in 1985.
But remember, one day the Courts can say "This is bullshit" and change course. For instance, as an Assistant Prosecutor, I've had to preemptively dismiss "Possession of Stun Gun" charges after the Feds indicated that the law was violative of the Second Amendment. Granted, if you still use it on someone as a weapon and the facts don't show that it was being used justifiably, you can still be charged with using a weapon unlawfully. But, the law in the NJ books states that possession of a stun gun on its face is per se illegal. Since the Courts have told us otherwise, we react accordingly.