From a gameplay standpoint, it seems that pikes are meant to be the "well you didn't get any iron, so here is something to hold you over until Renaissance". On a side-note, this is also one of the reasons the AI is programmed to bee-line Civil Service, since it is much more difficult to program an AI to effectively get iron than it is to just make them spam pikes.
The problem, as Unresolved points out, is that you are not at the supposed advantage with iron and swords or long swords. Yes, long swords have a higher base strength to go up against any unit, including both knights and pikes. And yes, all that experience carries over into muskets and beyond (where as pike upgrade line kind of dies off). But universities with specialists makes such a significant difference, the sacrifice isn't worth it. That is 6 base science and 33% modifier along with the GP points--to compensate for that, you need to conquer a ton of cities and that just isn't going to happen with swords unless it is lower difficulties, in which case you don't need the science anyway.
I can see where the devs were going with the idea: Top of the tech tree is assuming you have the taller cities for specialists to cover for having less cities; bottom of the tech tree is assuming the military tech will allow you to build up a huge science base by going wider. Unfortunately even on lower difficulties where you can take multiple cities with ease, it is extremely difficult to keep pace with the huge jumps in science from bee-lining those science techs and buildings.
Straying a bit off-topic, but between the iron-less meat shields and the much better tech path, long swords are nothing more than a short stopping point until muskets.
Although should be noted that due to the AI's free techs and ability to rack up science without the tech (growth, unlimited happiness, and ICS)--France AI can pull off some nasty musketeer rushes, since he is one of the few AI that doesn't push Civil Service. If only the human player could go straight to muskets while dropping new cities every few turns and hitting crazy population even without tile improvements.
The problem, as Unresolved points out, is that you are not at the supposed advantage with iron and swords or long swords. Yes, long swords have a higher base strength to go up against any unit, including both knights and pikes. And yes, all that experience carries over into muskets and beyond (where as pike upgrade line kind of dies off). But universities with specialists makes such a significant difference, the sacrifice isn't worth it. That is 6 base science and 33% modifier along with the GP points--to compensate for that, you need to conquer a ton of cities and that just isn't going to happen with swords unless it is lower difficulties, in which case you don't need the science anyway.
I can see where the devs were going with the idea: Top of the tech tree is assuming you have the taller cities for specialists to cover for having less cities; bottom of the tech tree is assuming the military tech will allow you to build up a huge science base by going wider. Unfortunately even on lower difficulties where you can take multiple cities with ease, it is extremely difficult to keep pace with the huge jumps in science from bee-lining those science techs and buildings.
Straying a bit off-topic, but between the iron-less meat shields and the much better tech path, long swords are nothing more than a short stopping point until muskets.
Although should be noted that due to the AI's free techs and ability to rack up science without the tech (growth, unlimited happiness, and ICS)--France AI can pull off some nasty musketeer rushes, since he is one of the few AI that doesn't push Civil Service. If only the human player could go straight to muskets while dropping new cities every few turns and hitting crazy population even without tile improvements.