Not only that, but when it says something like "Virgin Trains train" it will sound ridiculous.
If they think "service" is somehow bad they could try "departure".
Agreed that "departure" is better, partly because it's a cognate in many other languages (note how Eurostar always use "departure" rather than "service," as do most other continental railway operators who make announcements in English. Airports will always announce a "flight" or a "departure" too, rather than a "service.")
How can they see the word service a bad though? Wonder what went into it to result in the change.
"Service," simply speaking, might not compute in an occasional passenger's mind to "train" - or in the mind of someone for whom English isn't their first language, or someone who has learning difficulties. In my view it's generally better to use a word that more obviously describes that it is a train you can get on to get to your destination.
This isn't to say the word "service" doesn't have its place. It just might be better to say "train" in some contexts. (There are some cases where "service" is not the best word to use at all, such as a certain Guard who once instructed passengers to "move down inside the service" - he clearly meant "move inside the train/carriage.")