I can't add anything onto this. It's too good. BRAVOYeah, what can I say.. I don't think the duals seem very interesting for extroverts when younger, it's only when you get more experience you start to understand even the fact that there are wildly different personalities and it actually matters. I think for SLE (or extroverted and sensing types in general) it's easy to just go for the good-looking and exciting people at first until after enough disappointments you realize something about duality, perhaps after meeting one accidentally.
I find it a bit difficult to put into words, but IEI are the perfect combination of mysterious insight, subtle but delightfully dramatic and mocking Fe and ability to not be offended by rudeness. They seem to be amazed of your capability to do mundane and trivial things while living in this intriguing dreamworld. Interacting with IEI is never boring because while they do very little in the real world, all those mental explorations result in a lot of unexpected insights and while impractical they usually seem very smart in philosophical ways and are eager to understand the world. They just need help with the perception of the static reality, confirming what is real and what isn't, help with practical things and sometimes a bit of push to venture out in the world and actually do things using their body instead of their mind. I don't see them as useless. Sure, they might not perform these practical mundane boring tasks very well, but it's the mind of an IEI that is an endless source of interesting conversations, funny expressions and vocal impressions. IEI are the masters of using their voice to convey emotions, truly dramatic or often in the form of mockery. Making fun of other people is something both SLE and IEI enjoy. The world-rejecting quality of Ni-Se is reflected in the tastes that beta NF have for disturbing, otherworldly unreal and even violent art. The tastes of Ne/Si valuers often seem bland and mundane in comparison.. too soft, wholesome and infantile.
IEI have the capability of predicting social outcomes very well and can help the SLE to not make social blunders that they sometimes make due to brashness that results in social backlash. However being irrationals, they don't mind a bit of chaos and rule-breaking..
To summarize, I definitely think IEI have a lot to offer to the SLE, it's just not in the form of practical things. It's their superbly weird insightful minds, suitably demure sweetness and capacity for forgiveness. SLE often have a problem of being dissatisfied with anything they have, forever reaching for something more. Enjoying what you have in the moment is not for ignoring Si. With an IEI you can somehow exist outside time and reality for a while and feel happy. That is enough. They don't need to be productive or capable in the physical world. They can inject meaning into the most basic mundane things. Se in itself just sees things as they truly are, devoid of feelings, potentalities or meaning and sometimes this can feel depressingly banal.