Why do some Muslims fast on the 9th and 10th moharram even when it was abandoned by the Prohpet (saw)?

Below are narrations which shows it was abandoned Sahih Muslim .No 2510 > Abd al-Rahman b. Yazid said: When al-Ash'ath b. Qais entered the house > of 'Abdullah he was having his breakfast. He ('Abdullah b. Umar) said: > Abd Muhammad (al-Asha'th), come near to the breakfast. Thereupon he > said: Is not today the day of 'Ashura? He ('Abd al-Rahman) said: Do > you know what the day of 'Ashura is? He said: What is it? He said: It > is a day on which the Messenger of Allaah (sallAllaahu alayhi wa > sallam) used to observe fast before the (fasting) in the month of > Ramadan (became) obligatory. But when it became obligatory the > (fasting of 'Ashura) was abandoned (as compulsory). Abu Kuraib said: > He (the Prophet) abandoned it. Sahih Muslim .No 2511 > This hadith has been narrated from Jarir on the authority of A'mash > with the same chain of transmitters and he said (these words with a > little bit of variation from the previous hadith): When (fasting) in > Ramadan was (made) obligatory, he aban- doned it (the practice of > observing fast on Ashura). Sahih Muslim No 2512 > Qais b Sakan reported that al-Ash'ath b. Qais went to 'Abdullah on the > day of 'Ashura while he was eating. He said: Abu Muhammad, come near > and dine. Upon this he said: I am fasting. Thereupon he said: We used > to observe fast and then (this practice) was abandoned. Sahih Muslim 2514 > Jabir b Samura reported that the Messenger of Allaah (sallAllaahu > alayhi wa sallam) commanded us to observe fast on the day of Ashura > and exhorted us to do it and was particular about it But when > (fasting) in Ramadan was made obligatory, he hence. forth neither > commanded us nor forbade us, nor was he so particular about it Sahih Bukhari: vol 3 . book 31 hadith 116 : Narrated Ibn 'Umar: > The Prophet observed the fast on the 10th of Muharram ('Ashura), and > ordered (Muslims) to fast on that day, but when the fasting of the > month of Ramadan was prescribed, the fasting of the 'Ashura' was > abandoned. 'Abdullah did not use to fast on that day unless it > coincided with his routine fasting by chance. If it is abandoned why Muslims still fast those days?