And role-playing is better when I can actually express the thoughts and feelings of a character, rather than just having them in my head and the world around me pretending they don't exist.
Matter of opinion. I like playing characters who keep their own counsel about their deepest held feelings and beliefs - especially since I don't expect writers and animators to adequately present the variety that different characters might hold.
I also know that just because a fictional character - or actual person in real life - isn't emoting does not mean they are empty.
Should they remove all of the character dialogue too since you can just pretend you're best friends with Garrus and in a relationship with Liara?
I could, as long as the writers don't actively deny it. I can also imagine that fictional characters eat, shower, crap, fill out reports, and have sex more than once per game - even though the game doesn't show any of it.
This is a game with dialogue and a dialogue wheel, allowing you to express thoughts or feelings.
Some. Not all.
I'd hope Shepard's mind is on the battle when waiting for the next waves of enemies (unless he isn't loyal yet, of course), but sure, there is some room to imagine things onto the character.
I'm not sure where loyalty of the protag comes into play.
"Mind is on the battle" can take many forms. Shepard might be thinking about how many more might be coming, where they'll come from, whether the crew is optimally positioned for the onslaught, which weapons and ammo loads to use - and a whole lot of other things. She might be feeling apprehensive, confident, worried about how squadmates will react or fare. Etc.
That's true of every game, no matter how much or little you're allowed to characterize the character. What's your point?
What was yours?
And yet the game allows you to express what you think of the new Normandy, Cerberus, the Genophage, the Geth, ect. But not the single most significant thing to happen to the character; death and resurrection.
Most of the opinions Shepard can express are very superficial. Death and resurrection are far more complex and would delve deeply into a character's most strongly held and cherished beliefs - and that's assuming the character was 1- willing to talk about them, and 2- had an audience with whom she was willing to talk about them.
Yeah, and those videos and that conversation were a game late. It wasn't the right time and place at all.
The writers disagree with you.
"Space Magic" being the answer doesn't preclude the characters from asking questions or discussing it.
Just how would those conversations go?
Q: How did they bring you back to life?
A: Space magic.
or, maybe
A: I don't know. Miranda killed the doctor, and Cerberus doesn't share tech.
As for Philosophical and religious implications, your excuse is invalidated by these very games bringing up those issues. Ashley discusses her faith in Mass Effect, again allowing Shepard to express an opinion on something less important than their own death and resurrection, and Mordin discusses philosophy and religion both on his loyalty mission and in relation to the Collectors. Thane also jumps into philosophy/religion.
Those things are NPCs philosophies and beliefs, not Shepard's. Any opinion or feedback Shepard expresses is superficial at best.
When? Shepard asks TIM about the old crew once at the beginning and says "ok" when TIM says they are unavailable.
Shepard can ask Jacob and Joker about the old crew.
In any case, I'm probably finished with this discussion. I don't expect anything useful or enlightening will come of it.