No, there's no reason to trust the NSA's motivations. I'm just not sure what the NSA's motivations have to do with this.

If you're asking, "do we actually need lightweight ciphers", well, the NSA isn't the only organization designing them; it's a whole field of research. If you want cryptographic security on machines that don't have multipliers and count their capacity for program text space in single-digit kilobytes, you're probably going to reach for special-purpose designs.