Some people, including myself, would like to see a return of the 2E monster write ups that included much more than just mechanical stats. I'm not big on a whole page of mechanics myself, its the less crunchier stuff Im after.
Some people, including myself, fround the 2e monster writeups to be just plain obnoxious, leading to something that would be either ignored or cookie-cutter, presenting e.g. "A typical goblin tribe" as the only real organisation and sentences like "For every 40 goblins there will be a leader and his 4 assistants, each having 1 Hit Die" to be horribly deterministic. For me the high point of monster fluff came in, of all things, the 4e Monster Manual 1.
The first thing the 4e MM1 did right was presented differences between monster types in name and mechanics, so your standard kobold militia was called a "kobold tunneller" and your specialist ranged kobold was a "kobold slinger" whose sling shot pots of nasty stuff rather than being an archer. Meanwhile the standard goblin spellcaster wasn't a "level 2 goblin wizard" but a "goblin hex-hurler" with their private spells really selling the nasty and obnoxious nature of hex-hurling as a goblin speciality and how it makes them different from gnome illusionists.
The second thing the 4e MM1 did right was to present suggested encounters in each broad monster type. Sometimes this was dull, the equivalent of "An adult male lion, an adult female lion, and their two cubs" (with three different statblocks) while from memory the Aboleth entry and the Drow entry both included slaves of other species and most of them indicated a social hierarchy due to the multiple different types involved.
What I'd like to see is, for the sapient creatures, three separate organisations of a single paragraph each. For example:
The Knife Cave goblins are the third largest tribe in the Torpenhow Hills and are known locally for their intricate woad tattoos and their massacre of their rivals the Stark Ridge goblins despite the customary truce at the midwinter festival. The tribe itself consists of about seventy adult goblins, all combatants and at any given time a couple of dozen non-combatant goblins under twelve. Their leaders are Ruby the Bloody Handed, a [champion template] and their elder Naggla the Grey, Speaker for Kel'thaz [warlock template]. Scouting and raiding parties, frequently looking for livestock that in lean times may be human or dwarf, consist of not less than a dozen goblins lead by one of Ruby's four current favourites with only Sapphire and Cutter having remained longer than two years, or by Naggla's apprentice Flint.
The Varren's Quarter goblins are a goblin enclave in the city of Lavadeep. One of the poorest parts of Lavadeep, about 300 of the 500 people living there are goblins, making their living how they can. and packing like sardines into the slum because they know they need little room. Most of them can fight, having demonstrated the hard way that just because goblins are small and relatively weak they aren't prey, and a lot of them make their living with low paid work that doesn't require brute strength, often as messengers where their ability to slip through gaps can give them an edge, or house servants who are light on their feet because they don't weigh much and who can be quite literally overlooked by employers who would think it gauche to acknowledge a servant. More highly paid goblins include craftsmen, tinkers, entertainers, and vets (although few of other races will willingly go to goblins for medical care). Famous goblins within the community include 
The goblins within Buldgutz greenskin horde are...
All of which says a lot about goblins and how they are seen within the world and provides far more hooks than the dull 2e Monstrous Manual without saying that that's the only way to do things.