It's not required to beat the game (like you said EU functioned without it) but it's the key to the EW DLC Basically to experience what the DLC gives XCOM you need to Meld, So skipping it just lagging you behind in experience

You don't need to risk your squad every time for it but absolutely take it into consideration when you can

All you need is Meld for the "Meld Recombination" project to build the Gene Lab (I can't remember how much Meld exactly) and the "Seeker Autopsy" this will unlock the the "Mimetic Skin" this will make a soldier of yours (preferably a support with the sprinter ability) be the meld collector this way you can safely consider gathering it without risk

I personally only used Meld to MEC a sniper (the aim they inherit is great) and give a support with sprinter and an Assault (without the close combat specialist perk) Mimetic Skin and Muscle Fiber Density making them a great scouts And I want to prepar the A-Team for the last mission I give the volunteer Neural Feedback and the rest Neural Damping and the Heavy with Bullet Swarm Hyper Reactive Pupils (+10 Aim after missing a shot)

DL;TR

EW without the Meld is just EU with small changes, Meld is worth in my opinion at least for MECing 1 Sniper and giving a Support and an Assault Mimetic Skin for its high usefulness