The issues with this are precedent/slippery slope. Today it's a small stake in a small number of companies, but empirically government initiatives almost always grow. Once entrenched, I would be willing to bet that the government will take larger and larger stakes in a bigger and bigger number of companies until this model becomes a non-trivial, potentially dominant, share of the economy. I can see myself becoming a single-issue voter to oppose that future (although given bipartisan support I'm unlikely to have any options; maybe Rand Paul).