Srimate Raamanujaye Namaha,

Swami, true we cannot interpret however we like. That is is we base on what acharyas have interpreted They have studied the characters of all personalities fully by hearing whole of Mahabharata , so they know the personalities fully than us.

Secondly if Arjuna is also considered bad, Duryodhana is also considered bad, then why should people  hear or read Mahabharata and what will they benefit or apply?

Thirdly what Arjuna did in the war , By making Lord Shri Krishna as a charioteer may have many reasons which we cannot understand. ( Lord’s plan, Glorify his devotees, shows how easily He is approachable etc.. so for any or many of these reasons Lord would have covered Arjuna’s intelligence)

Finally Duryodhana did not expand his territory but was unwilling to share the kingdom with his cousins, nor even give 5 villages. 

Adiyen

Srimathe Rangaramanuja Mahadesikaya Namaha

Thought provoking answer Swamy.

Here Arjuna is not to be considered bad nor
Dhuryodhanan be considered good

A person’s character cannot be adjudged by circumstances. They may have their own reasoning.

What is expanding territory?
Getting hold of other’s kingdom (property) correct?

Dasarathan did ashwamedha
Sri Ram did ashwamedha

How one captures kingdom is subjective
Shakuni rolling dice was no acceptable means to take over kingdom but it avoided bloodshed of people.

The same reason why Krishna went as Messenger to avoid bloodshed. War was last resort.

Kshatriya need to show power to retain or capture property. Failure of diplomatic relations is failure of Kingdom.

Dasanudasan