No Matter Where You Go, Everyone's Connected
At its very core, SEL is about connection, I think.
SEL was originally created by aBe to appeal to both Western and Eastern audiences, but for Western and Eastern fans to have very different views on it. It was kind of meant as an attempt to show how different West and East (specifically America and Japan) are, but I think it kind of backfired for the exact same reason it succeeded at the same time. Contradictory, I know, but stay with me here.
Lain has many connections across the series: some personal, but the vast, vast, vast, vast majority are impersonal. They're connections that exist, but that she doesn't necessarily feel connected to; they're the billions of people in and connecting with the Wired, which thanks to Protocol 7 has implanted itself in the subconscious mind of humanity as a whole. These connections aren't as important to Lain as her personal connections are; or, to expand on that a bit, the connections she wants to have.
Alice is a key example of this, and I think that she's Lain's most important relationship: Lain loves Alice from the bottom of her heart. It's a very deep and very important love for Lain; it's the only thing that could've realistically broken her from Masami's control, and we see it happen. Likewise, Alice loves Lain; if not loves, then at least has incredibly deep, caring, and complex feelings for her. Throughout the entire series, Alice is the only person we see actually care for Lain Iwakura: not Lain of the Wired, or Lain-as-God, or "Lain". Even her own father kind of kind of haphazardly dismisses her, her mother downright hates her, and Mika couldn't care less about her. Taro is interested in Lain, primarily for the Lain of the Wired as well as his role as a servant of the Knights, but I can't say he actually cares about her. Alice's friends more or less hang out with Lain because Alice does. Masami doesn't care about Lain in the same way that Alice does; his "care" is incredibly selfish, incredibly toxic, and incredibly abusive, whereas Alice is completely willing to put herself in harm's way or harm her relationship with other people to try and help Lain: just like Lain resets the memories of other people for her. Alice and Lain are both willing to go to extremes for the person they love, whereas Eiri exercises extremes only when he learns he cannot control Lain anymore.
At the same time, though, is the connection that Lain has with the rest of the world not important? In that vein, not potentially more important? We can comprehend Dunbar's Number: we can maintain social relationships with about 150 people. We can't comprehend the millions of people we connect with every day; we watch the same videos, we look at the same images, read the same books, watch/read the same news, laugh at the same jokes, play the same games, and so on. Even since the beginning of widespread international... well, connection after the Agricultural Revolution, humanity has been interconnected in some way or form.
It's not a direct connection. I know jack shit about any random 30 year old living in Jakarta or a 13 year old living in Tehran, aside from the fact that they live in Indonesia and Iran. But it's still a connection: it's a connection across time, across borders, across nations. When I'm reading, say, Marx, I'm reading the same books that people in the 1800s read; that inspired Lenin, Stalin, Mao, Luxemburg, Foster, and others (some of whom weren't even socialists, like Ataturk or Mussolini); that changed western philosophy in the last two centuries. I'm connecting with the millions, if not billions of people who have also read Marx; be they from 1856, 1917, or 2024. When I watch a video with 30 million views, I'm connecting with 30 million people; it's an indirect and impersonal connection, but we're all connected through watching that video.
The internet connects billions of people simply by its very existence. When you log into an internet connection, you are connecting to 5.35 billion other people. SEL understands that. Everybody in SEL is connected to the Wired; not just through hooking into it, but through Protocol 7 connecting all of humanity subconsciously, as well. Lain herself is the amalgam of that; she is not just a product of the Wired, or the God of the Wired, or God at all: she is the output, the child of that connection. In a sense, the connection itself.
That's what "Let's all love Lain!" really means, I think. It's a meme; an idea spreading from person to person in a culture. Or, contrary to what aBe might've expected, multiple cultures. It took over MAL about a year back, and it's become popular in both Japan and the States. "Let's all love Lain!" is the ultimate meme in SEL; it is the connection point, ultimately what connects everybody together in the end; their connection to the Wired, their love for Lain, their link to all other 8 billion people in the world.
"Protocol 7 is expected to allow the seamless transfer of information between the Wired and the real world." The message immediately after that?
Because, in this sense, we can all love Lain. Not directly, but indrectly; we may never actually know who Lain is, or what she is for that matter; but we can love her regardless through our interpersonal connections, and we can connect with each other impersonally or otherwise through the internet. If Lain is the Wired, then we can all love Lain; we can all love the connection to Lain; we can love our connections to each other; we can love each other.