Why is it that the Nazis were such pioneers in so much of the technology we use today?

They weren't. They were pioneers in the development of large long-range liquid fueled rockets (such as the V-2). The German scientists and engineers that were sought were rocket scientists/engineers.

For many technologies, such as radar, jet engines, analog computers, etc., the Allies had comparable or even better technologies. For some key post-war technologies, such as digital computers, atomic weapons, semiconductors, etc., the Allies were well ahead. These are much more everyday technologies than large long-range liquid-fueled rockets.

In the late 19th century and early 20th century, Germany was a world-leader in science and technology; at this time, German was a key language for the international communication of science. This was due in part to their invention of the modern research university and a strong high-tech industrial base. However, the adoption of the modern research university (and modern industrial research) by other countries eroded that lead, and the economic impact of WW1 and its loss by Germany, and the Depression, brought German science to its knees, a feeble thing compared to what it had been a few decades earlier (browsing through back issues of, e.g., Zeitschrift für Physik, should make the decline quite clear). The Nazis are often given a great deal of credit for destroying German science and research, but what they destroyed was an already ill and feeble creature (English had overtaken German as the main international language of science well before the Nazis took power in Germany).

The German lead in rocketry resulted from two things: the German army was very interested in rocketry, due to restrictions on German heavy artillery imposed by the Allies at the end of WW1 (and restrictions on the air force contributed to interest in rocketry, too). Germany funded rocketry research for military goals (that's reason 1) at a time when other countries left rocketry research to interested amateurs (that's reason 2). Their progress was not a result of any inherent German superiority in science and technology, but simply that they were doing research on a much larger scale and with better funding than other countries. Other countries were not without key pioneers (e.g., Goddard in the USA, Zander in the Soviet Union). German pioneers like von Braun got support from the army and state that the non-Germans didn't.

Another technology you mention, Enigma, was developed at the end of WW1 (by a German); the Nazis can't take any credit for Enigma (but they can take credit for being scientifically and technologically behind in codebreaking).

Germans made key advances in science and technology in the late 19th and early 20th centuries. Those days were long gone by the time of the Nazis. The Nazis were not supermen of science and technology.