Yes, Marco; it seems that the fact by which the pikes were useless is that under fire they became of little use; the pikers felt more as a target than a soldier, and dropped the pikes to get the musket of dead fellows. The advent of the fire weapons made these slow formations innefective.
Sorry if I am being unnecessarily sensitive (to your and mine feelings), but it was not my intention to criticize your great photos (you are too good in both photography and historical accurateness).
Indeed, I think your photograph is quite accurate, because I think that seems to be the most reasonable way in which a bayonet infantry can face cavalry. All other possible options seem inferior than just standwith the points facing the horses. You can't run away because cavalry is faster and you may make lose the battle. All you can is try to stop the horses by stabbing them, as with a pike.
The problem I think is this: a horse has much more strenght, velocity, mass and inertia than a man, thus, the pikers do not rely in their own force to stop cavalry, because it is inferior to that of the horses, thus they plant the pike butt into the soil, so that the horse's strenght is stopped by something stronger than a man. But bayonets seem too short to be planted on the soil... so even if you stab the horse, you cannot stop it and the infantry might be overwhelmed. The greater the velocity of the cavalry, the less likely it will be to stab a horse while avoiding to be under their feet.
I was thinking yesterday that perhaps the bayonet is better to fight other infantry. I thought... why to put a bayonet and not a man with a musket and a saber in the infantry? The armament would be heavier, but not so much. There is necessary more metal to waste, as a saber is bigger than a bayonet, but many rich countries may likely have afforded the cost of a saber for the front lines at least.
Perhaps to fight well with a saber, you must drop the musket, thus tending to lose it in the struggle. But I think that if you put two men in equality of conditions (force, agility), one with bayonet, the other with saber, the man with the saber has advantage, he can cut and stab, while the man with the bayonet on musket can only stab. However, there is an advantage the man with the bayonet has: the longer reach.
Although I think one on one the man with the saber would most likely win, I think that if the men with bayonets can manage to form a close, shoulder to shoulder unit, they can have adventage over saber infantry, in that they may stab when the other infantry comes into reach, before the sabers can have the necessary reach (it will be difficult for the saber infants to avoid the bayonets by dodging backwards given the forwards movement of the soldiers behind).
Sorry if all this is out of place... I just get interested in this stuff after reading on the use of the Macedonian sarissa (long spear used in hedgehog-like formations with which the Macedonians defeated the Greek hoplites, until then the best soldiers).