The reasons that SkyDemon flightplans are the way they are have evolved over many years of filing them. With hundreds of thousands filed, we have honed the output to be as useful as possible across the wide variety of countries and use cases we cover. I'll give some basic answers to your questions but these shouldn't necessarily be regarded as entirely comprehensive, as we are not in the business of documenting every reason why things are the way they are in our product.

1. Many countries want this pilot information transmitted in the original flightplan, which normally doesn't include item 19. So we include it.
2. I tried your link in three different browsers but it didn't work. I will ask our flightplan expert whether he thinks it might be appropriate to switch from a remark to the ORGN switch.
3. You say nobody cares; you're wrong. You're not the first person to think this is a vanity inclusion but a great deal of ANSPs have been able to contact us directly because we include this information in a more expeditious way than using the AFTN to reach us. Also it's been great for some ANSPs who wish to record the originator of electronic flightplans for statistical purposes.

Dear SkyDemon,

I have some questions and comments about how you send supplementary information in your ATS flight plans. This is compared to what I see at work as a controller, in flight plans coming from more conventional sources.

1) You put pilot name and phone number after the RMK/ switch in field 18. This would normally go in field 19 after the C/ switch and not transmitted in the regular flight plan to ATS. Should this information be needed, we simply request it from the originator.

2) Also in field 18 RMK/ you add "SUPP INFO RQS KBLIHAEX". There is an ORGN/ switch defined for this, why not use that?
https://contentzone.eurocontrol.int/FPL/item.aspx?id=180

3) "CREATED BY SKYDEMON". This feels like some email clients adding a "Sent from my iPhone" to the signature. It shouldn't be there, nobody cares. IMHO it makes you look amateurish...

Sorry to come off sounding negative. You have a great product, I use it all the time when I fly. Please consider this suggestions to make it even better.

Regards
Johan