Religious law has been breached on the Mount
This is the author's conclusion
"The breach of the rabbinical decision that forbids entry to the Temple Mount demonstrates that the strict religious law - regarding which we have always been told that not even a single comma in it can be changed - can in fact be updated in accordance with the changing political circumstances."
This is absolutely ridiculous. The writer completely misunderstands what is going on and the halachic process. Application of halacha is based on facts, when the facts change the application of the halacha changes. As RHS said, until now we applied Sif alef, now that the facts changed we need to apply Sif Beis. This is exactly what happened here.
The original prohibition was as the writer states because the Rabbis were not sure what was permissible and what was not and therefore the Rabbis said you can't go up. Since then (in the 38 years since) much research has been done to map out the Temple Mount. Based on this the Rabbis have delineated areas that are clearly permitted.
This is not the halacha changing but the facts and the corresponding application of the halacha changing. When the facts were not known the Rabbis prohibited, now that the facts have been clarified the application of the halacha changes accordingly and therefore you are permitted to go up.
The reasons for the research may be political/idealogical. In other words, in 1967 R' Zvi Yehuda probably thought that Moshiach was around the corner and therefore there was no need to deal with this. Now that everyone has realized that the process is a slow one (it doesn't look like we are any closer to Moshiach then we were in 1966), the need/want to allow people to go up has become much greater and therefore the Rabbanim researched the subject and looked into it. This is perfectly fine, and is not changing the halacha.
I implore everyone to respond to this article in Haaretz by posting comments and writing letters.