Can anyone appease Krishna by devotion alone?
It is not the character of Krishna to like someone due their personal traits. Krishna likes anyone, who follows the path of TRUTH and adheres to DHARMA, because Krishna himself does the same. Not only Arjuna, and Pandavas, but anyone, who follows the path of TRUTH and adheres to DHARMA, will be liked by Krishna. Please note that when Bhishma and Drona sided with Duryodhana, who did not adhere to DHARMA, Krishna got Bhishma and Drona eliminated. Krishna cannot be fooled by mere devotion shown to him, if one is not following the path of TRUTH and adhering to DHARMA. — When Krishna revived dead Parikshit, he uttered the following. न ब्रवीम्युत्तरे मिथ्या सत्यमेतद्भविष्यति । एष सञ्जीवयाम्येनं पश्यतां सर्वदेहिनाम् ॥ नोक्तपूर्वं मया मिथ्या स्वैरेष्वपि कदाचन । न च युद्धे परावृत्तस्तथा सञ्जीवतामयम् ॥ यथा मे दयितो धर्मो ब्राह्मणाश्च विशेषतः । अभिमन्योः सुतो जातो मृतो जीवत्वयं तथा ॥ यथाहं नाभिजानामि विजयेन कदाचन । विरोधं तेन सत्येन मृतो जीवत्वयं शिशुः ॥ यथा सत्यं च धर्मश्च ...