Usually Islam is associated with the sunnah. Without the sunnah, there is not much difference between Judaism, Christianity and Islam. The sunnah usally emphasises on the manner of doing things.
Generally Muslims do not really practise most of the sunnah because of being in a different age of time and influence from other cultures. This is one example of the sunnah that I find from Ibn Qayyim's book Al-Tibb al-Nabawiya (Healing with the medicine of the Prophet salallahua'laihiwasalam).
The Prophet salallahua'laihiwasalam said: "I do not eat while leaning on my side." He also said, "I only sit like the slave sits and eat like slave eats."
Leaning on the side harms the stomach because it prevents the food from going down the proper channel and reaching the stomach quickly, as it pressures the stomach and does not allow it to be open properly for the food to pass through.
Eating while leaning on something is the practice of the arrogant people and this is why the Prophet salallahua'laihiwasalam said that "I only eat like the slave eats."
The Prophet salallahua'laihiwasalam used to sit on his feet while eating. He used to place his knees on the ground and would place the bottom of his left foot on the upper part of his right foot in humility for the Lord and in respect for the food and for those present. This is the best way to sit for eating, because the organs of the body will all be in their proper position, along observing good manners.
The sunnah that is being mentioned is about the guidance on the proper way to sit while eating, is not really being practised in recent times. Most of us have furniture (dining tables, chairs and etc) and it will be awkward and weird if we do not have those. Hence, because of having furnitures, we do not really get the chance to practise the sunnah unless in a function where furniture consume too much space.
I would find a house without dining tables and chairs very weird myself if I did not know this sunnah. Anyway, the value of the sunnah is not really being appreciated. From my limited knowledge and research, There are a few reasons why we would find it awkward and weird not having dining tables and chairs..
1)The perception of being a backward and traditional family.
2)The perception of not having the capability to buy furnitures (not posh enough)
3)The influence and mentatlity of western culture is better/advance than the east.
All these factors have caused an important sunnah not to be practised. This is because being too conscious of the perception from the wider community of "not being fit/posh enough". Dining tables and chairs are a luxury and in the age we live in today, it has somehow turned to a neccessity. Can you imagine what is the neccessity of the future? Is it important for us to be living in luxury? Why are we so conscious about the perception of the community when we should be afraid from Allah?
If we were to practise the sunnah, it would be considered as a good deed which will be benificial in the hereafter (akhirah) and will also be beneficial to our health in this world (dunya). In a way I respect the Japanese for their ability to preserve some of their lifestyle which commonly associates with humility.