If you're looking at it solely from the male character's perspective, perhaps. But when it comes to female characters in fiction, I prefer seeing their arcs defined on their own terms rather than treating them merely as subordinate facets of a male character's arc. From Lana's own perspective, the storyline gave her empowerment, independence, and a new heroic destiny. She wasn't just some man's love interest who got away; the end of the story for Clark was the beginning of the story of the rest of Lana's life, a story that would define her for her own actions and abilities, not merely as some man's object of desire.
Lana became "empowered" in a far too literal sense for it to be taken as actual character growth. The only way she was able to rise above being little more than a love interest was to become the second most powerful humanoid on the planet? This doesn't strengthen her character, it weakens it into an eggshell.
Earlier in the story, Lex desired her as a precious object, not as a human. He didn't treat her with any human respect, but coerced her love with manipulation and utilized huge resources to fake a pregnancy. At this stage, and through the first seasons with other boyfriends, Lana showed a very adolescent personality typical of a teenage girl: She saw her self-worth as measured by the worth of her boyfriend.
When Lana finally clued in to Lex's manipulations, she realized how powerless she was, not just from her economic status or physical strength, but her personality. She went dark, kidnapped Lionel, etc. "Dark Lana" was by far her most interesting hour, and it
should have been the catalyst for Clark realizing she wasn't a fairy-tale princess.
I believe that Lana's video-taped goodbye to Clark was forced by Miller and Gough having to leave the series and to write in a short space what they would have preferred to drag out for another season. That said, this was Lana's moment of true growth. She could see herself as an individual, realized she had to discover the world and her worth as an individual, and not just be the arm candy of the best boyfriend she could hook up with. Personally I see this as Lana's empowerment and independance.
We shouldn't see Lana's empowerment and independance as suddenly aquiring superpowers. We should see it as the day she realized she could go out into the world on her own. That was the day she grew up. This was the end of the teenage Lana and the beginning of her adult life.
But with the Lana-return arc, we see again that Lana herself is defining who Lana Lang is in terms of how she fits into her boyfriend's (super powered Clark) life. In order to be with him, she needs superpowers. She is not enough by herself. She needs body modification to be worth of being at his side. This is little more than a metaphor for a boob-job. Her arc was the equivalent of some other woman getting some silicone implants to be worthy of getting married to a successful boyfriend. That doesn't speak empowerment to me, it speaks of a personality that is broken.
In order to fit into the show, Lana has to be perfect. She has to be the perfect desirable cheerleader. She has to be the perfect lover who will always be there for Clark, even after years of forced separation. She has to be faster than a speeding bullet and more powerful than a locomotive. She has to be all of these things, supposedly, according to the writers. Personally I think she didn't have to be, I think she was a better character when she showed believable weakness, when she lost it and sought dark revenge the way many of us would if we'd been manipulated like the Luthors did to her. But the way the writers ended up needing to turn her into a perfect machine, this was her Mary Sue destiny, because she couldn't do it with any realistic character growth.