From the Morrowind Script Extender v2 documentation:
It seems to me that Lua scripting may be the future of Morrowind modding now that it is being incorporated into the Morrowind Script Extender (MWSE). I am wondering how much MWSE functionality is being built into OpenMW, including Lua scripting, and how this will effect the availability of mods to users of OpenMW.Starting in MWSE 2.1, modders are able to create powerful, event-driven modifications to The Elder Scrolls III: Morrowind using the Lua scripting language.
Unlike traditional mwscript, Lua scripting is responsive. Instead of checking every frame to see if an object is being activated, a mod might register to see if their reference was activated.