Why exactly?
Food and drinks service on board will be the same as all other Monarch flights and they'll be a few Monarch cabin crew on board to ensure customer service levels are maintained. The only difference between flying on a Monarch aircraft and an Aurela one is the interior, which while it may be older, is probably just as comfortable.
750XL, call me illogical but there is, with respect, a difference.
When I buy a brand it speaks something to me about why they do what they do. Flying on a clapped out Lithuanian a/c, however safe etc, is just not the same as on a Monarch badged and operated machine. I understand the reasons for doing it but, in my opinion, it's a bad business move.
I repeat my earlier question - when passengers booked these flights were they aware that they would be flown by a Lithuanian airline?