cranking for a few seconds before starting is a good thing--with our race engines, we always ''crank for oil pressure'' before powering up the ignition/ starting...i ran my tPi for years with the 9th injector unplugged, to build oil pressure before loading the engine bearings (present lt1 intake doesn't have a cold start injector)
''instant light-up'' is a marketing device, and gives the operator a thrill, but is really not the best way for the engine to enjoy a healthy and long life.
sudden change from ''instant light-up'' is most likely due to deteriorated performance of a fuel system component...get a $15 fuel pump test kit at harbor fright and screw it onto the fuel rail test port (temporary test only -- do NOT leave the gauge on permanently)...pressure should go to abt 40 psi as soon as ign key is turned ''on'', and should hold 10 psi after 12 hour sit (key off)
there is slight chance that your ''extended cranking'' may only be due to your gasoline vendor having already switched to ''summer'' fuel formula with lower RVP, which will not vaporize properly in cool ambient.