Why is it not wipe and wipe when there's so much evidence for both?

Thank you for your sincere inquiry! As for the supposed proofs for wiping, our imams regard them as inauthentic and unplausible due to the evidences otherwise. There are very clear statements from our imams that the wiping of the feet is invalid as well as the narrations that support it. Imam Rassi (as) said in his treatise, Kitaab Salaat al-Yawm wa al-Layla:

We say to the Rafidites who advocate for wiping the feet: “From where do you say this, which is in contradiction to the descendants of al-Hasan and al-Hussein, upon them be peace?" If they say that it is because their imams advocated for this and they necessitate its acceptance, we say: So the imams gave you something that they hadn’t given to their descendants and made you to do something from Allah’s guidance that they hadn’t made their relatives do? By such, you connect to the unrelated stranger and sever their ties from the beloved relative.

Thus, Imam Rassi, upon him be peace, denies that this practice was transmitted from al-Hasanayn and their descendants. Furthermore, he says in the treatise Al-Masaa´il al-Qaasim: 

Regarding wiping the feet, none advocate for that except those who agree with the companions of the Imami Shi’ites. However, nothing has reached us from any of the Progeny of the Messenger except what is contrary. One is to wash them and not wipe them.

It is further substantiated in the Musnad Imam Zayd that the feet are to be washed and not wiped. Notice the chain of transmission. It says: 

Abu Khalid al-Wasiti said narrated that Imam Zayd b. 'Ali narrated from his father Imam 'Ali b. al-Hussein who narrated from his grandfather Imam al-Hussein b. 'Ali that the Commander of Believers, Imam 'Ali b. Abi Talib, peace be upon them all, said " I saw Allah's Messenger, peace and blessings be upon Him and His Progeny, perform the ritual ablution and he washed his face and his arms three times, rinsed his mouth and nose three times, wiped his head and ears once and washed his feet three times." 

Thus, this practice is linked to the imams in the earliest source. 

As for the existence of those reports in which the Prophet, peace and blessings be upon him and his progeny, purportedly wiped his feet, it is plausible that such ablution was done while he already had ritual purity. That is to say that those reports probably related that he performed such wudu for extra reward and not because he needed to. A similar report is narrated in which Imam 'Ali, upon him be peace, did such. The following report appears in Sharh at-Tajreed:

It is narrated on the authority of an-Nazaal b. Sabra that ‘Ali, upon him be peace, prayed the noon prayer and stayed with the people in Rahba. Some water was brought to him, and he rubbed his face, arms, head and feet with it. He drank the surplus and then said: “Some people claim that this is discouraged, but I saw Allah’s Messenger, peace and blessings be upon him and his progeny, do the same as I just did. This is the ablution for one who hadn’t invalidated his ritual ablution.”

Thus, it is more likely that those reports--if they are indeed authentic--in which the Prophet, peace and blessings be upon him and his progeny, wiped his feet in the ablution only demonstrate an ablution for one who already had ritual purity. Such is also the case in those reports in which the Prophet, peace and blessings be upon him and his progeny, was said to have wiped over his sandals and/or leather socks.  

And Allah knows best!

IRS

Thank you for your question!

It is generally assumed that Imam Nasir (as) advocated for the feet to be wiped. However, this is a mistake because the view he actually held to was that the wiping of the feet during the washing is what is an obligation. It does not mean that he held to the view that the wiping alone is sufficient. Imam Mahdi Ahmed, upon him be peace, related in his Al-Bahr that the collective Prophetic Descendants held to the view that the feet are to be washed without exception. The only advocates for wiping that he mentions are the Imamiya and Zahiriya. 

And Allah knows best!

IRS