Shouldn't we take Lord Buddha's word above the all others? I have seen many answers to questions referring teachings of modern teacher in this SE.

But as i have learned 

Lord Buddha's understanding is above any other,even above an arahant.

Dhamma/Dharma itself is timeless and therefore does not need modifications or updates.



So what is the need of the term "Modern practice / Modern Buddhism"?

Shouldn't we take Lord Buddha's word above the rest and use any other resource later on for further clarification if there is such a need?

Why there is a trend of drifting away from original teachings, does the followers now believe that Lord Buddha's words are outdated?
It is correct, that the Dhamma is both universal and timeless.

The Dhamma is described as being an ancient path, that fully enlightened Buddhas discover by themselves and then teach it to other beings.

The words from a fully enlightened Buddha need not to be renewed or changed.

One needs only to practice insight meditation to find out if these words are true or not.

So there is no need for renewal of the Dhamma. The Dhamma is complete as it is. The Dhamma does not change.

Don't worry about the shifting away from the Dhamma. That is bound to happen. That is why there will arrive a future Buddha. The next fully enlightened Buddha to be, is Maitreya, whom arrives when the Dhamma has been completely forgotten. That is just the nature of a world system.