For those who don't like and don't eat 'bar food', it's no loss - for those that do like that option - it's painful because Boardwalk once had two such options and now has none.
Food trucks are great, in my opinion - but there are quite a few things they can't 'replace' - who knows if Disney will keep the outside tables where Big River was, but likely not - the food trucks usually just have stand-up tables set up around them - someone looking for a restaurant to sit down, in the air conditioning, have a waiter refilling drinks, etc - a food truck is not equivalent.
The fact that the food truck hours seem to be for lunch only means at dinner time or after park hours, means there are no options at all in the evening.
I'm not 100% sure if the food trucks will all be fully compatible with Disney's pay system or not - hopefully they will because many people head out with nothing but a Magic Band and don't bring cash or credit cards.
The sports-bar concept is something a lot of people enjoy - beers and drinks, lots of TVs playing various sports, and comfort foods/appetizers rather than healthy fare or high-end chef creations. Even some of us who love a good 5-star restaurant and excellent service may not want that every night - so mixing in a relaxed sports bar one night is a great option.
Food trucks by their nature are a 'temporary' solution - they're not there all the time, there's no seating or wait service, and they usually have limited hours and limited supplies. Now if they were to park several food trucks on the Boardwalk, leave them there 11am to 11pm, have supplies brought out to the truck from nearby refrigerators, keep the indoor seating area of Big River open for use by the food truck patrons, and allow you to place an order and sit with a beeper and have wait staff bring the food to your table...then maybe that really could be a replacement for ESPN or Big River.
Especially lately, Disney has plenty of QS options, plenty of healthy fare, and plenty of mid to higher-end sit down restaurants. One thing it has lacking now is sports bar restaurants - as far as I can think, only three remain in two locations: Rix at Coronado, and City Works, and Splitsville at Disney Springs. Just a few years ago, Boardwalk had two.