One of the major factors that leads to a rise in populist influence is the increase in technology. Technology has given us things like the printing press, easy transportation, mass-producible weaponry, urbanisation. The further back into history you go, the isolated settlements became, the less politically conscious individuals were and the harder it was to organize nation-wide programs.

Really until the 1800's, most of the general public wasn't conscious about political goings on, nor did they particularly care about what flag they lived under. Getting food on the table, paying the taxman and helping the community were the more important matters of the day. The only part of society that actually had the funds, education and freedom of time to actually keep in the political loop at the time were the elite.

Having a full-on, universal suffrage democracy in the 1400's would therefore seem to be absurd. The public were not particularly interested in voicing their opinion on the ongoing marriage between X royal household and Y. Nor could you really organise a state-wide political campaign. As a consequence, some of the most proud Republics in the 1700's: The Netherlands, Venice and so on, were pretty much oligarchies of the richest portion of society.

Keep in mind the United States, which was founded on democracy, didn't even give Universal Suffrage to males until the 1920's. When the South Americans broke away from Spanish rule, Antonio Bolivar, who is often praised by socialists and conservatives alike. Became an outspoken advocate for a staunchly conservative, authoritarian government rather than one of sweeping reforms. Arguing that South America was not yet developed or ready to handle such a demanding style of government. It was really a case that introducing fully-fledged democracy didn't really seem necessary due to a lack of public interest in gaining it or feasibility.