My two cents:
1. Kohli has swagger in his personality and is handsome as well... Tendulkar was genius as a batsmen but his personality was average, he was nor handsome(by any standards) neither had any swagger... In Pakistan because of these decencies he may not have such a big icon
2. Kohli also has won India many pressure games, specially in sub continent, those matches are watched by lot more people because of time zone differences... Also, now people can watch matches which are not played with Pakistan only, 20/25 years ago you only watch matches of your country...
3. Kohli has also being very good against Pakistan, single handily won many matches, SRT really won 2003 WC match, rest hardly resonate with Pakistanis... Kohli has just won two big ones in two months, not to mention WC 2015 match...
4. Kohli is chase king, not just for India but best in the world, that is something Pakistanis never had (maybe Miandad back in 80s), this is also our biggest weakness... You appreciate lot more when somebody does that we so much consistency and ease.
5. Recent Kohli and Amir friendship has won many fans heart... He had shown lot of respect for Amir, who did not got much love from most ex-cricketers and teammates, that resonates with many fans...
Also, keep in mind people loved Mitch Johnson a lot during his hot Ashes series, cricketer loves including Pakistani fans enjoyed his purple patch... Sometimes people enjoy great cricket... There are lot of Dhoni's fan too, because of his ice cool temperament and the way he finishes!!!