The only time I've eaten in my room was when the EB was running really late last summer (surprise!) and we were served KFC in our rooms. The meals had been sitting outside for at least an hour or so, so the food wasn't great, but I did enjoy eating in the room.
I know this is a "controversial" topic, so one time (also on the EB, different trip) we had a really good SCA who had to take every meal to a large party that took up several rooms. She was constantly running to the dining car and back for that group. When she had a free moment, I asked her about serving people in their rooms & her thoughts about offering it. Basically, her response is that the work day for a good SCA was already packed with more than enough work, and that when in-room meals were added in, she just had too much work to do & not enough time to do it.
I think part of it is Amtrak's fault - the packaging they use just isn't friendly for carrying multiple meals through a crowded train. Everything should be able to fit into one bag (instead of multiple plastic-covered containers). Cans of soda, empty cups, and a bag of ice in another bag. That way, the SCAs could carry everything to the rooms in one trip & not have to worry about spilling or missing anything.
Part of the problem is the food - most of the amtrak diner food just isn't designed to be "to go." A sandwich or burger can easily be wrapped in paper and eaten in a roomette without utensils, but a plated meal that requires a knife and fork or has a very "liquid" side dish will be harder. Cold desserts are also a problem, as they could melt by the time your meal is finished. Fortunately, the Amtrak ice cream is usually frozen rock-hard, and you need to wait at least 30 minutes until a spoon can scrape a few chunks off the block.
Another problem (especially in my SCA's case) can be the passengers themselves. It sounds like most of you ask the SCA for in-room meals well ahead of time, and allow them to serve you whenever it's convenient. Many pax don't do that, and wait until the SCA is in the middle of a busy service stop to try to get their attention for meals. Also, it's a lot easier on the SCA if people remember all the condiments, salad dressings, silverware, etc. that they want ahead of time, instead of asking the SCA to make repeated trips to the dining car for things they forgot.
So no, I've never eaten a regular meal in my room. Count me in the group that thinks that eating with strangers is awkward. As support for that, I'd like to point out that 99.999% of regular restaurants do not require you to sit with strangers. However, the current arrangement just makes it difficult for most people on Amtrak to do otherwise.