The user:read:email scope is only required if you need the endpoint to return the users email address. You can use any OAuth token you like, it’s just that if it lacks that scope for the user you’re attempting to look up, the email field will be omitted.
If you wish to submit a feature request the appropriate place would be Uservoice https://twitch.uservoice.com/forums/310213-developers but in this situation to add profile image urls to the Get Followed Streams endpoint it would be needlessly bloating the data that’s returned and going off the standard of returning the ‘stream’ object which doesn’t include profile banner images as that’s not a property of a stream.
Ideally your app should make a request to Get Users and then cache the response for a period of time so that you don’t need to make additional requests for the same data every time.