For the length of a journey on the 385 are the lamps really necessary? The lights being bright is perhaps unfortunate for some (including me!), but, arguably, it does make some level of sense to provide a bright cabin as this will be theoretically easier for folks with impairments such as visual problems, and, could also be argued to be a Health and Safety improvement. Naturally of course, if the lighting is too bright then you'd expect it could perhaps be adjusted.
Edit: The relevant part of the
franchise agreement (Sch 6.1 app2, 9.12 on page 329) as regards ambience might also help to explain the lighting:
"The Franchisee shall ensure that the interior design of the saloons and vestibules shall provide an open aspect that avoids enclosed unlit areas. The ambience shall be one that reduces the perceived threat to passengers with particular consideration for the elderly, single females and other vulnerable groups."