I think you may be missing a bit of the nuance of the IKEA effect - it's not about superfluous assembly, but rather providing a context in which a little bit of user effort is massively amplified to produce results otherwise unobtainable. Take a look at the chart of the sweet spot for IKEA effect: high value with high contribution and minimal effort. The contribution the user puts into the final IKEA product is really huge - going from a flatpack of scraps to a complete piece of furniture - while the effort to do so is arguably pretty minimal.