Linked from
The 7 pages that link to Taq polymerase, each with the reason it gives.
DNA polymeraseBroader topic: Its heat tolerance made repeated high-temperature PCR cycles practical.
ExtremophileBroader topic: Its heat tolerance made repeated high-temperature steps in PCR practical.
ThermophileBroader topic: Its ability to withstand repeated heating made it central to early PCR.
Kary MullisBroader topic: Its heat tolerance made repeated PCR heating practical.