It is all very inconsistent of course, particularly when Melissa's death gets completely dropped and only mentioned again in time for the next mythology episode, but still it does feel like those episodes are the biggest ones for focusing on Mulder and Scully's characters, that they are the ones that introduce the long-lasting emotional stakes and the big cliffhangers. I'm not sure it's fair that they often get completely dismissed these days in favour of the MotW episodes. Yeah there were a lot of classic MotW episodes of course, but there were also a fair few that felt quite inconsequential compared to the epicness that you got in say the Nisei/731 two-parter for example, and you can really see why the mythology episodes maybe made a bigger impact at the time. (At least I think it was the case that originally most fans argued for the conspiracy episodes over the MotW episodes, and now it's the reverse?)

The events in mythology episodes are what create the unique bond between Mulder and Scully. Without them, the series would be much less compelling, and fans today conveniently forget that. I think two things frustrate people about the mytharc. It's internally inconsistent because Chris Carter never bothered with details--even the basic facts like Mulder's memories about his sister's abduction changed from season to season. The other problem is that nothing is ever resolved to anyone's satisfaction. Seasons eight and nine made matters worse by introducing new mythology--the super soldiers--whose origins and purpose are never satisfactorily explained.

Don't get me started on season ten. Everything about the mytharc in seasons 1-9 was a lie? The CSM survived being fire-bombed? BREAKING UP MULDER AND SCULLY?! It was a travesty.