As far as Argentina goes, you have to look at the geography of the region. Historically, the heart of Chile has been the region in what's now Central Chile around the capital, Santiago. This region of Chile is bounded by the Andes mountains on the east which provide a fairly difficult to penetrate border due to the very high elevation of the passes. As Argentina and Chile set their sights south on expansion into Patagonia, there was some conflict that was resolved diplomatically to result in the borders they have today, but I'm unfortunately not well versed in that subject to really expand beyond that.

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For Bolivia, their situation is the result of the War of the Pacific. To give a very, very brief introduction, the northern reaches of Chile today used to belong to Peru and Bolivia. Antofagasta to Tocopilla was Bolivian, while Iquique to Arica was Peruvian. While the region is home to the desolate Atacama Desert, it's actually a fairly valuable region to this day thanks to its valuable silver and copper deposits, and in the mid-1800s it was perhaps even more important for its nitrate deposits (important for fertilizer and high explosives). The border disputes themselves date to colonial times, but the situation immediately leading up to the war is vaguely reminiscent of the Mexican-American War - the regions administered by Bolivia and Peru came to be populated largely by Chileans, and the inevitable problems that sprung from that eventually gave Chile casus belli to invade and take on the Bolivian-Peruvian alliance in 1879.

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Unfortunately for Bolivia, they weren't very well prepared for the war. They had a coast but no significant navy, with naval action being almost exclusively a Chilean-Peruvian affair. Chile was economically, politically, and militarily better suited for the war, and, while Bolivia's situation allowed it better access across the Andes than Argentina, it still suffered from the fact that its heartland was in the highlands far removed from the coast with very limited means to reinforce things. While Peru and Chile could both ferry in reinforcements via ship (in fact the bulk of the campaigning consisted of Chile landing troops at critical points on the coast), Bolivia had to bring men and supplies across the mountain passes of the Andes and desolate deserts of the Atacama. Bolivia was removed from active participation in the war fairly quickly, and the final years of the war ended up being a more drawn-out affair as Chile tried to subjugate the Peruvian interior to bring Peru to the peace table.

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While it took Bolivia quite a while to finally accept the realities on the ground, the new borders that cut Bolivia off from the sea largely reflect the geographic limits of the region. Like further south in Chile, the borders are the Andes mountains, but with the presence of the Atacama in the region, the bulk of the population is right up along the coast. As far as "fairness" to Bolivia goes, while the Pacific Coast is certainly a point of contention to this day, the geographical barriers in the region really limited its usefulness to Bolivia, and I've seen it argued that the territorial losses in the Chaco War were more damaging due to the loss of access to the Paraguay River, which was more accessible to the Bolivian heartland and had navigable access to the sea.