Sims stand/sit somewhere else instead of eating at table

Sorry if there is a report for this already but I could not see one, but its starting to get to me that every time my sims go out to dine they get up from seat when the food is delivered  and ether stand and eat it or walk off and eat, its a pain I want a dining experience with the people there with,  not them walking off.

I am playing on xbox next gen

This happens to me too!

They even go to toilet sometimes with plate in their hands...

No mods. No CC. PC.

I don't know if it's a design choice by the developers but hear me out:

If a sim lives alone and eats alone, they eat at the dining table no problem, but if there's another sim in the house either a visitor or a housemate, they walk over to where they happen to be sitting (watching TV, reading etc.) even if it's in the living room or whatever then they sit beside them in the couch / other chair where they proceed to eat with their plate in hand. They aren't even chatting with each other while the other sim grabs a serving from the fridge or the counter. You eat at the dining table even if other people are doing their own thing in their own spaces. This never was a thing in Sims 1 and 2. 

I am having the same issue, especially when eating at the restaurants in the Dine Out pack. They would request a table, sit down, and immediately get up. I have to constantly queue my sims to sit.

Playing with no mods or CC on PC.

Same here - No mods, no cc, PC  I'm having the same eating habits.  I've started telling them to sit on a dining chair at the table, but I have to be quick or they will march off.   

• In Sulani the lot Admiral's wreck, I made the wrecked boat into a gym.  The hungry sim will take their plate and walk out of the house to the underground gym where 1 or 2 sims are working out.  
• The sim will grab a leftover and stand in front of the fridge to eat instead of sitting at the counter or dining table.  

If I may add something (as I mostly play in community lots), this also happens when ordering something at the bar. The Sim asks for food, the bartender places it on the counter. The Sim gets up, takes the plate, walks around, and sits down in a random place. When the "order a drink" interaction works and is not cancelled, the same happens. The Sims have to get up to grab the cocktail, even if they are sitting in front of the bartender. This wasn't the case years ago, I'm sure of that.

The answer is simple, but annoying: Sims are obsessively NEEDY.  They will go to great lengths not to do something ALONE if there are other Sims available.  It's the same reason that they will go sit on someone else's BED while they are SLEEPING just to read there.