I understand what you are saying that to you it does not seem worth investing into characters for the reward but I don't think you understand ROI.
ROI is a mathematical equation ROE=(Return-Cost)/Cost. So if it cost you 5 Mil to get 1 Mil your ROE would be a -80% and that is really bad. But ROI does not take into account duration of a return. After 5 weeks your return would be 5 Mil thus making ROI= 0% every week after the 5th week the ROI would continue to grow. after 10 weeks your return would be 10 Mil and your ROI would then be 100%.
So, the question then comes to what is the opportunity cost to not have a scoundrel team and miss out on potential credits (opportunity cost is basically what what you would be missing out choosing plan A over plan B). I think the opportunity cost of ignoring the event is probably why people may disagree with you. From the earliest time you could possibly start earning credits from his event to the # of weeks you actually complete the event is going to equal so many credits. That compared to how far you drop in arena and miss out on those rewards is what you need to weigh on what plan is more economical. Arena, GW, and this event are not mutually exclusive so you can have a high arena rank, you can get GW credits and get these awards.
I can see if you always are #1 in arena that maintaining that ranking is probably a top priority and farming for this event may be lower on the list but 1. It is very hard to always be #1 in arena and 2. Maintaining rank in arena is not as difficult farming wise because you generally only need to max out 5 characters. Being able to get the increased amount of credits allows players to adjust with the changes in the game. I was sitting in the top 10 in arena then RG was buffed and I dropped for a period of time because I did not have the credits needed to get RG maxed quick enough. This is why I think this event is so great more credits allows for a faster pace leveling up of characters that helps allow anyone to grow they way they need to.
A major component of this game is built around managing resources. As you get higher levels you must start choosing do I invest to be better in Raids, Arena, etc. I see the opportunity of gaining 1 Mil a week helping anyone do any of these.
