"There have been complaints about the high costs for a growing license plus capital requirements making it prohibitive for small timers to enter the industry. Buy isn't that the whole point of regulation in the first place?"
To a large degree, exactly so. More regulation favors large established companies and results in large companies having de facto oligopolies with high barriers to new entrants.
This is why large companies are often the biggest proponents for more regulations - it helps them to smother competition. A great example is to compare the computer and internet industries which had very little regulation to the petroleum refining and electric power generation industries which are highly regulated. The barriers to new entrants in the computer and internet industries are low, new products and services are rolled ~OUTT weekly - cost per unit of performance continues to decline dramatically. Contrast to the fact that the US has nott built a single new refinery since 1977 (Lake Charles, LA) and prices spike when our limited refining capacity goes into maintenance shutdowns, summer/winter switchovers, and accidents; refining is an oligopoly market, especially in the most highly regulated areas like California with consistently the most expensive gas outside of Hawaii). Or contrast to the electric power generation industry, where prices have been increasing substantially and there is little to no innovation or meaningful competition - just endless rate hikes in a monopoly marketplace.
As odd as it may seem to those on the Left, regulation is the tool of large corporations - they love to force regulations that conform to their abilities and detriment their existing or potential competitors. Recently, some have popularized the phrase 'regulatory capture' - and this is very true - large corporations use the governmental regulatory powers and authorities to do their bidding, by tailoring regulations which stifle competition and the need to innovate, giving them quasi-monopolies or oligopolies with pricing power and no sense of urgency to produce new or better products and services.
The same is happening in marijuana. The major problem with the 2016 California proposition that legalized marijuana is that the regulations will absolutely drive small and medium producers and sellers ~OUTT of the market. And the price of cannabis products will no doubt rise and rise as the industry becomes dominated by a few large players - who will lobby for more and more regulation.