game design - Does an inventory limit in an MMORPG make sense?

I am currently developing a simple 2d MMORPG. My current focus is the inventory system.

I am currently wondering if I should implement a limit on what a player character can carry. Either in form of a maximum weight, a limited number of inventory slots, or a combination of both. Almost every MMORPG I ever played limits inventory space. But plausibility aside, is this really necessary from a gameplay point of view? Maybe it would in fact improve the game experience when I just let the players carry as much stuff as they want.

tl;dr: What is the game development rationale behind limiting carrying capacity of player characters?

Edit: Thanks for all the answers so far. They all were very insightful. After your input I decided to go for a limited inventory to prevent people from carrying too many healing items and too much specialized equipment into dungeons. To avoid the problem of loot overload and having to return to the town all the time, I plan to give players the ability to send items from their inventory directly to their storage (but not the ability to retrieve them in the field). I accepted the answer by Kylotan for now, but do not let this discourage you from posting additional answers, when you feel that some interesting aspect wasn't covered yet.

Answer

Much of game design is about resource management, because deciding how best to use limited resources is an interesting choice that games can easily implement. Limiting the inventory forces players to think about the value of each item and make decisions on whether to hoard or sell their loot, and on which items to carry out into battle with them.